diff --git a/executable_semantics/ast/expression.cpp b/executable_semantics/ast/expression.cpp
index f5e3fb4430f5..ddb8f838d425 100644
--- a/executable_semantics/ast/expression.cpp
+++ b/executable_semantics/ast/expression.cpp
@@ -30,7 +30,7 @@ auto ExpressionFromParenContents(
 auto TupleExpressionFromParenContents(
     int line_num, const ParenContents<Expression>& paren_contents)
     -> const Expression* {
-  return global_arena->New<TupleLiteral>(
+  return global_arena->RawNew<TupleLiteral>(
       line_num, paren_contents.TupleElements<FieldInitializer>(line_num));
 }
 
diff --git a/executable_semantics/ast/expression_test.cpp b/executable_semantics/ast/expression_test.cpp
index a0139a49655f..a404484968be 100644
--- a/executable_semantics/ast/expression_test.cpp
+++ b/executable_semantics/ast/expression_test.cpp
@@ -55,7 +55,8 @@ TEST(ExpressionTest, UnaryNoCommaAsExpression) {
   // ```
   ParenContents<Expression> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<IntLiteral>(/*line_num=*/2, 42)}},
+                    .term =
+                        global_arena->RawNew<IntLiteral>(/*line_num=*/2, 42)}},
       .has_trailing_comma = false};
 
   const Expression* expression =
@@ -67,7 +68,8 @@ TEST(ExpressionTest, UnaryNoCommaAsExpression) {
 TEST(ExpressionTest, UnaryNoCommaAsTuple) {
   ParenContents<Expression> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<IntLiteral>(/*line_num=*/2, 42)}},
+                    .term =
+                        global_arena->RawNew<IntLiteral>(/*line_num=*/2, 42)}},
       .has_trailing_comma = false};
 
   const Expression* tuple =
@@ -81,7 +83,8 @@ TEST(ExpressionTest, UnaryNoCommaAsTuple) {
 TEST(ExpressionTest, UnaryWithCommaAsExpression) {
   ParenContents<Expression> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<IntLiteral>(/*line_num=*/2, 42)}},
+                    .term =
+                        global_arena->RawNew<IntLiteral>(/*line_num=*/2, 42)}},
       .has_trailing_comma = true};
 
   const Expression* expression =
@@ -95,7 +98,8 @@ TEST(ExpressionTest, UnaryWithCommaAsExpression) {
 TEST(ExpressionTest, UnaryWithCommaAsTuple) {
   ParenContents<Expression> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<IntLiteral>(/*line_num=*/2, 42)}},
+                    .term =
+                        global_arena->RawNew<IntLiteral>(/*line_num=*/2, 42)}},
       .has_trailing_comma = true};
 
   const Expression* tuple =
@@ -109,9 +113,11 @@ TEST(ExpressionTest, UnaryWithCommaAsTuple) {
 TEST(ExpressionTest, BinaryAsExpression) {
   ParenContents<Expression> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<IntLiteral>(/*line_num=*/2, 42)},
+                    .term =
+                        global_arena->RawNew<IntLiteral>(/*line_num=*/2, 42)},
                    {.name = std::nullopt,
-                    .term = global_arena->New<IntLiteral>(/*line_num=*/3, 42)}},
+                    .term =
+                        global_arena->RawNew<IntLiteral>(/*line_num=*/3, 42)}},
       .has_trailing_comma = true};
 
   const Expression* expression =
@@ -125,9 +131,11 @@ TEST(ExpressionTest, BinaryAsExpression) {
 TEST(ExpressionTest, BinaryAsTuple) {
   ParenContents<Expression> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<IntLiteral>(/*line_num=*/2, 42)},
+                    .term =
+                        global_arena->RawNew<IntLiteral>(/*line_num=*/2, 42)},
                    {.name = std::nullopt,
-                    .term = global_arena->New<IntLiteral>(/*line_num=*/3, 42)}},
+                    .term =
+                        global_arena->RawNew<IntLiteral>(/*line_num=*/3, 42)}},
       .has_trailing_comma = true};
 
   const Expression* tuple =
diff --git a/executable_semantics/ast/pattern.cpp b/executable_semantics/ast/pattern.cpp
index 23d7c06b3306..4c3b99902450 100644
--- a/executable_semantics/ast/pattern.cpp
+++ b/executable_semantics/ast/pattern.cpp
@@ -59,7 +59,7 @@ TuplePattern::TuplePattern(const Expression* tuple_literal)
   const auto& tuple = cast<TupleLiteral>(*tuple_literal);
   for (const FieldInitializer& init : tuple.Fields()) {
     fields.push_back(Field(
-        init.name, global_arena->New<ExpressionPattern>(init.expression)));
+        init.name, global_arena->RawNew<ExpressionPattern>(init.expression)));
   }
 }
 
@@ -77,7 +77,7 @@ auto PatternFromParenContents(int line_num,
 auto TuplePatternFromParenContents(int line_num,
                                    const ParenContents<Pattern>& paren_contents)
     -> const TuplePattern* {
-  return global_arena->New<TuplePattern>(
+  return global_arena->RawNew<TuplePattern>(
       line_num, paren_contents.TupleElements<TuplePattern::Field>(line_num));
 }
 
@@ -101,7 +101,7 @@ auto ParenExpressionToParenPattern(const ParenContents<Expression>& contents)
   for (const auto& element : contents.elements) {
     result.elements.push_back(
         {.name = element.name,
-         .term = global_arena->New<ExpressionPattern>(element.term)});
+         .term = global_arena->RawNew<ExpressionPattern>(element.term)});
   }
   return result;
 }
diff --git a/executable_semantics/ast/pattern_test.cpp b/executable_semantics/ast/pattern_test.cpp
index 76a20a94c0ac..ff6e74fbd741 100644
--- a/executable_semantics/ast/pattern_test.cpp
+++ b/executable_semantics/ast/pattern_test.cpp
@@ -52,7 +52,7 @@ TEST(PatternTest, UnaryNoCommaAsPattern) {
   // ```
   ParenContents<Pattern> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<AutoPattern>(/*line_num=*/2)}},
+                    .term = global_arena->RawNew<AutoPattern>(/*line_num=*/2)}},
       .has_trailing_comma = false};
 
   const Pattern* pattern = PatternFromParenContents(/*line_num=*/1, contents);
@@ -63,7 +63,7 @@ TEST(PatternTest, UnaryNoCommaAsPattern) {
 TEST(PatternTest, UnaryNoCommaAsTuplePattern) {
   ParenContents<Pattern> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<AutoPattern>(/*line_num=*/2)}},
+                    .term = global_arena->RawNew<AutoPattern>(/*line_num=*/2)}},
       .has_trailing_comma = false};
 
   const TuplePattern* tuple =
@@ -75,7 +75,7 @@ TEST(PatternTest, UnaryNoCommaAsTuplePattern) {
 TEST(PatternTest, UnaryWithCommaAsPattern) {
   ParenContents<Pattern> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<AutoPattern>(/*line_num=*/2)}},
+                    .term = global_arena->RawNew<AutoPattern>(/*line_num=*/2)}},
       .has_trailing_comma = true};
 
   const Pattern* pattern = PatternFromParenContents(/*line_num=*/1, contents);
@@ -88,7 +88,7 @@ TEST(PatternTest, UnaryWithCommaAsPattern) {
 TEST(PatternTest, UnaryWithCommaAsTuplePattern) {
   ParenContents<Pattern> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<AutoPattern>(/*line_num=*/2)}},
+                    .term = global_arena->RawNew<AutoPattern>(/*line_num=*/2)}},
       .has_trailing_comma = true};
 
   const TuplePattern* tuple =
@@ -100,9 +100,9 @@ TEST(PatternTest, UnaryWithCommaAsTuplePattern) {
 TEST(PatternTest, BinaryAsPattern) {
   ParenContents<Pattern> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<AutoPattern>(/*line_num=*/2)},
+                    .term = global_arena->RawNew<AutoPattern>(/*line_num=*/2)},
                    {.name = std::nullopt,
-                    .term = global_arena->New<AutoPattern>(/*line_num=*/3)}},
+                    .term = global_arena->RawNew<AutoPattern>(/*line_num=*/3)}},
       .has_trailing_comma = true};
 
   const Pattern* pattern = PatternFromParenContents(/*line_num=*/1, contents);
@@ -115,9 +115,9 @@ TEST(PatternTest, BinaryAsPattern) {
 TEST(PatternTest, BinaryAsTuplePattern) {
   ParenContents<Pattern> contents = {
       .elements = {{.name = std::nullopt,
-                    .term = global_arena->New<AutoPattern>(/*line_num=*/2)},
+                    .term = global_arena->RawNew<AutoPattern>(/*line_num=*/2)},
                    {.name = std::nullopt,
-                    .term = global_arena->New<AutoPattern>(/*line_num=*/3)}},
+                    .term = global_arena->RawNew<AutoPattern>(/*line_num=*/3)}},
       .has_trailing_comma = true};
 
   const TuplePattern* tuple =
diff --git a/executable_semantics/ast/statement.cpp b/executable_semantics/ast/statement.cpp
index 6c5234fa54f4..7c2639176ebb 100644
--- a/executable_semantics/ast/statement.cpp
+++ b/executable_semantics/ast/statement.cpp
@@ -132,7 +132,7 @@ void Statement::PrintDepth(int depth, llvm::raw_ostream& out) const {
 
 Return::Return(int line_num, const Expression* exp, bool is_omitted_exp)
     : Statement(Kind::Return, line_num),
-      exp(exp != nullptr ? exp : global_arena->New<TupleLiteral>(line_num)),
+      exp(exp != nullptr ? exp : global_arena->RawNew<TupleLiteral>(line_num)),
       is_omitted_exp(is_omitted_exp) {
   CHECK(exp != nullptr || is_omitted_exp);
 }
diff --git a/executable_semantics/common/BUILD b/executable_semantics/common/BUILD
index d9bfc1afc657..d7e11fe48ced 100644
--- a/executable_semantics/common/BUILD
+++ b/executable_semantics/common/BUILD
@@ -9,6 +9,7 @@ cc_library(
     srcs = ["arena.cpp"],
     hdrs = ["arena.h"],
     deps = [
+        ":ptr",
         "@llvm-project//llvm:Support",
     ],
 )
@@ -31,6 +32,15 @@ cc_test(
     ],
 )
 
+cc_library(
+    name = "ptr",
+    hdrs = ["ptr.h"],
+    deps = [
+        "//common:check",
+        "@llvm-project//llvm:Support",
+    ],
+)
+
 cc_library(
     name = "tracing_flag",
     srcs = ["tracing_flag.cpp"],
diff --git a/executable_semantics/common/arena.h b/executable_semantics/common/arena.h
index b42e4b02c7d8..8c9e0b799452 100644
--- a/executable_semantics/common/arena.h
+++ b/executable_semantics/common/arena.h
@@ -8,6 +8,7 @@
 #include <memory>
 #include <vector>
 
+#include "executable_semantics/common/ptr.h"
 #include "llvm/Support/ManagedStatic.h"
 
 namespace Carbon {
@@ -16,10 +17,20 @@ class Arena {
  public:
   // Allocates an object in the arena, returning a pointer to it.
   template <typename T, typename... Args>
-  auto New(Args&&... args) -> T* {
+  auto New(Args&&... args) -> Ptr<T> {
     auto smart_ptr =
         std::make_unique<ArenaEntryTyped<T>>(std::forward<Args>(args)...);
-    T* raw_ptr = smart_ptr->Instance();
+    Ptr<T> ptr = smart_ptr->Instance();
+    arena.push_back(std::move(smart_ptr));
+    return ptr;
+  }
+
+  // TODO: Remove. This is only to help findability during migration.
+  template <typename T, typename... Args>
+  auto RawNew(Args&&... args) -> T* {
+    auto smart_ptr =
+        std::make_unique<ArenaEntryTyped<T>>(std::forward<Args>(args)...);
+    T* raw_ptr = smart_ptr->Instance().Get();
     arena.push_back(std::move(smart_ptr));
     return raw_ptr;
   }
@@ -40,7 +51,7 @@ class Arena {
     explicit ArenaEntryTyped(Args&&... args)
         : instance(std::forward<Args>(args)...) {}
 
-    auto Instance() -> T* { return &instance; }
+    auto Instance() -> Ptr<T> { return Ptr<T>(&instance); }
 
    private:
     T instance;
diff --git a/executable_semantics/common/ptr.h b/executable_semantics/common/ptr.h
new file mode 100644
index 000000000000..044458f63d1e
--- /dev/null
+++ b/executable_semantics/common/ptr.h
@@ -0,0 +1,43 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#ifndef EXECUTABLE_SEMANTICS_COMMON_PTR_H_
+#define EXECUTABLE_SEMANTICS_COMMON_PTR_H_
+
+#include <memory>
+#include <vector>
+
+#include "common/check.h"
+
+namespace Carbon {
+
+// A non-nullable pointer. Written as `Ptr<T>` instead of `T*`.
+template <typename T>
+class Ptr {
+ public:
+  explicit Ptr(T* ptr) : ptr(ptr) { CHECK(ptr != nullptr); }
+
+  template <typename OtherT,
+            std::enable_if_t<std::is_convertible_v<OtherT*, T*>>* = nullptr>
+  Ptr(Ptr<OtherT> other) {
+    return Ptr<OtherT>(other.ptr);
+  }
+
+  Ptr(std::nullptr_t) = delete;
+
+  Ptr(const Ptr& other) = default;
+  Ptr& operator=(const Ptr& rhs) = default;
+
+  auto operator*() const -> T& { return *ptr; }
+  auto operator->() const -> T* { return ptr; }
+
+  T* Get() const { return ptr; }
+
+ private:
+  T* ptr;
+};
+
+}  // namespace Carbon
+
+#endif  // EXECUTABLE_SEMANTICS_COMMON_PTR_H_
diff --git a/executable_semantics/interpreter/dictionary.h b/executable_semantics/interpreter/dictionary.h
index cc1063c55c68..95058b780148 100644
--- a/executable_semantics/interpreter/dictionary.h
+++ b/executable_semantics/interpreter/dictionary.h
@@ -37,8 +37,8 @@ class Dictionary {
   // Associate the value v with key k in the dictionary.
   // Time complexity: O(1).
   auto Set(const K& k, const V& v) -> void {
-    head = global_arena->New<ListNode<std::pair<K, V>>>(std::make_pair(k, v),
-                                                        head);
+    head = global_arena->RawNew<ListNode<std::pair<K, V>>>(std::make_pair(k, v),
+                                                           head);
   }
 
   typedef ListNodeIterator<std::pair<K, V>> Iterator;
diff --git a/executable_semantics/interpreter/interpreter.cpp b/executable_semantics/interpreter/interpreter.cpp
index 33b34324ef85..017a0ce0643c 100644
--- a/executable_semantics/interpreter/interpreter.cpp
+++ b/executable_semantics/interpreter/interpreter.cpp
@@ -84,29 +84,29 @@ auto EvalPrim(Operator op, const std::vector<const Value*>& args, int line_num)
     -> const Value* {
   switch (op) {
     case Operator::Neg:
-      return global_arena->New<IntValue>(-cast<IntValue>(*args[0]).Val());
+      return global_arena->RawNew<IntValue>(-cast<IntValue>(*args[0]).Val());
     case Operator::Add:
-      return global_arena->New<IntValue>(cast<IntValue>(*args[0]).Val() +
-                                         cast<IntValue>(*args[1]).Val());
+      return global_arena->RawNew<IntValue>(cast<IntValue>(*args[0]).Val() +
+                                            cast<IntValue>(*args[1]).Val());
     case Operator::Sub:
-      return global_arena->New<IntValue>(cast<IntValue>(*args[0]).Val() -
-                                         cast<IntValue>(*args[1]).Val());
+      return global_arena->RawNew<IntValue>(cast<IntValue>(*args[0]).Val() -
+                                            cast<IntValue>(*args[1]).Val());
     case Operator::Mul:
-      return global_arena->New<IntValue>(cast<IntValue>(*args[0]).Val() *
-                                         cast<IntValue>(*args[1]).Val());
+      return global_arena->RawNew<IntValue>(cast<IntValue>(*args[0]).Val() *
+                                            cast<IntValue>(*args[1]).Val());
     case Operator::Not:
-      return global_arena->New<BoolValue>(!cast<BoolValue>(*args[0]).Val());
+      return global_arena->RawNew<BoolValue>(!cast<BoolValue>(*args[0]).Val());
     case Operator::And:
-      return global_arena->New<BoolValue>(cast<BoolValue>(*args[0]).Val() &&
-                                          cast<BoolValue>(*args[1]).Val());
+      return global_arena->RawNew<BoolValue>(cast<BoolValue>(*args[0]).Val() &&
+                                             cast<BoolValue>(*args[1]).Val());
     case Operator::Or:
-      return global_arena->New<BoolValue>(cast<BoolValue>(*args[0]).Val() ||
-                                          cast<BoolValue>(*args[1]).Val());
+      return global_arena->RawNew<BoolValue>(cast<BoolValue>(*args[0]).Val() ||
+                                             cast<BoolValue>(*args[1]).Val());
     case Operator::Eq:
-      return global_arena->New<BoolValue>(
+      return global_arena->RawNew<BoolValue>(
           ValueEqual(args[0], args[1], line_num));
     case Operator::Ptr:
-      return global_arena->New<PointerType>(args[0]);
+      return global_arena->RawNew<PointerType>(args[0]);
     case Operator::Deref:
       FATAL() << "dereference not implemented yet";
   }
@@ -124,12 +124,12 @@ void InitEnv(const Declaration& d, Env* env) {
       // Bring the deduced parameters into scope.
       for (const auto& deduced : func_def.deduced_parameters) {
         Address a = state->heap.AllocateValue(
-            global_arena->New<VariableType>(deduced.name));
+            global_arena->RawNew<VariableType>(deduced.name));
         new_env.Set(deduced.name, a);
       }
       auto pt = InterpPattern(new_env, func_def.param_pattern);
       auto f =
-          global_arena->New<FunctionValue>(func_def.name, pt, func_def.body);
+          global_arena->RawNew<FunctionValue>(func_def.name, pt, func_def.body);
       Address a = state->heap.AllocateValue(f);
       env->Set(func_def.name, a);
       break;
@@ -152,7 +152,7 @@ void InitEnv(const Declaration& d, Env* env) {
           }
         }
       }
-      auto st = global_arena->New<StructType>(
+      auto st = global_arena->RawNew<StructType>(
           struct_def.name, std::move(fields), std::move(methods));
       auto a = state->heap.AllocateValue(st);
       env->Set(struct_def.name, a);
@@ -166,7 +166,8 @@ void InitEnv(const Declaration& d, Env* env) {
         auto t = InterpExp(Env(), signature);
         alts.push_back(make_pair(name, t));
       }
-      auto ct = global_arena->New<ChoiceType>(choice.Name(), std::move(alts));
+      auto ct =
+          global_arena->RawNew<ChoiceType>(choice.Name(), std::move(alts));
       auto a = state->heap.AllocateValue(ct);
       env->Set(choice.Name(), a);
       break;
@@ -205,27 +206,27 @@ void CallFunction(int line_num, std::vector<const Value*> operas,
           PatternMatch(fn.Param(), operas[1], globals, &params, line_num);
       CHECK(matches) << "internal error in call_function, pattern match failed";
       // Create the new frame and push it on the stack
-      auto* scope = global_arena->New<Scope>(*matches, params);
-      auto* frame = global_arena->New<Frame>(
+      auto* scope = global_arena->RawNew<Scope>(*matches, params);
+      auto* frame = global_arena->RawNew<Frame>(
           fn.Name(), Stack(scope),
-          Stack<Action*>(global_arena->New<StatementAction>(fn.Body())));
+          Stack<Action*>(global_arena->RawNew<StatementAction>(fn.Body())));
       state->stack.Push(frame);
       break;
     }
     case Value::Kind::StructType: {
       const Value* arg = CopyVal(operas[1], line_num);
-      const Value* sv = global_arena->New<StructValue>(operas[0], arg);
+      const Value* sv = global_arena->RawNew<StructValue>(operas[0], arg);
       Frame* frame = state->stack.Top();
-      frame->todo.Push(global_arena->New<ValAction>(sv));
+      frame->todo.Push(global_arena->RawNew<ValAction>(sv));
       break;
     }
     case Value::Kind::AlternativeConstructorValue: {
       const auto& alt = cast<AlternativeConstructorValue>(*operas[0]);
       const Value* arg = CopyVal(operas[1], line_num);
-      const Value* av = global_arena->New<AlternativeValue>(
+      const Value* av = global_arena->RawNew<AlternativeValue>(
           alt.AltName(), alt.ChoiceName(), arg);
       Frame* frame = state->stack.Top();
-      frame->todo.Push(global_arena->New<ValAction>(av));
+      frame->todo.Push(global_arena->RawNew<ValAction>(av));
       break;
     }
     default:
@@ -260,9 +261,9 @@ void CreateTuple(Frame* frame, Action* act, const Expression* exp) {
         {.name = tup_lit.Fields()[i].name, .value = act->Results()[i]});
   }
 
-  const Value* tv = global_arena->New<TupleValue>(std::move(elements));
+  const Value* tv = global_arena->RawNew<TupleValue>(std::move(elements));
   frame->todo.Pop(1);
-  frame->todo.Push(global_arena->New<ValAction>(tv));
+  frame->todo.Push(global_arena->RawNew<ValAction>(tv));
 }
 
 // Returns an updated environment that includes the bindings of
@@ -422,16 +423,16 @@ void StepLvalue() {
       // -> { {E(x) :: C, E, F} :: S, H}
       Address pointer = GetFromEnv(exp->LineNumber(),
                                    cast<IdentifierExpression>(*exp).Name());
-      const Value* v = global_arena->New<PointerValue>(pointer);
+      const Value* v = global_arena->RawNew<PointerValue>(pointer);
       frame->todo.Pop();
-      frame->todo.Push(global_arena->New<ValAction>(v));
+      frame->todo.Push(global_arena->RawNew<ValAction>(v));
       break;
     }
     case Expression::Kind::FieldAccessExpression: {
       if (act->Pos() == 0) {
         //    { {e.f :: C, E, F} :: S, H}
         // -> { e :: [].f :: C, E, F} :: S, H}
-        frame->todo.Push(global_arena->New<LValAction>(
+        frame->todo.Push(global_arena->RawNew<LValAction>(
             cast<FieldAccessExpression>(*exp).Aggregate()));
         act->IncrementPos();
       } else {
@@ -441,8 +442,8 @@ void StepLvalue() {
         Address field = aggregate.SubobjectAddress(
             cast<FieldAccessExpression>(*exp).Field());
         frame->todo.Pop(1);
-        frame->todo.Push(global_arena->New<ValAction>(
-            global_arena->New<PointerValue>(field)));
+        frame->todo.Push(global_arena->RawNew<ValAction>(
+            global_arena->RawNew<PointerValue>(field)));
       }
       break;
     }
@@ -450,11 +451,11 @@ void StepLvalue() {
       if (act->Pos() == 0) {
         //    { {e[i] :: C, E, F} :: S, H}
         // -> { e :: [][i] :: C, E, F} :: S, H}
-        frame->todo.Push(global_arena->New<LValAction>(
+        frame->todo.Push(global_arena->RawNew<LValAction>(
             cast<IndexExpression>(*exp).Aggregate()));
         act->IncrementPos();
       } else if (act->Pos() == 1) {
-        frame->todo.Push(global_arena->New<ExpressionAction>(
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(
             cast<IndexExpression>(*exp).Offset()));
         act->IncrementPos();
       } else if (act->Pos() == 2) {
@@ -465,8 +466,8 @@ void StepLvalue() {
             std::to_string(cast<IntValue>(*act->Results()[1]).Val());
         Address field = aggregate.SubobjectAddress(f);
         frame->todo.Pop(1);
-        frame->todo.Push(global_arena->New<ValAction>(
-            global_arena->New<PointerValue>(field)));
+        frame->todo.Push(global_arena->RawNew<ValAction>(
+            global_arena->RawNew<PointerValue>(field)));
       }
       break;
     }
@@ -475,7 +476,7 @@ void StepLvalue() {
         //    { {(f1=e1,...) :: C, E, F} :: S, H}
         // -> { {e1 :: (f1=[],...) :: C, E, F} :: S, H}
         const Expression* e1 = cast<TupleLiteral>(*exp).Fields()[0].expression;
-        frame->todo.Push(global_arena->New<LValAction>(e1));
+        frame->todo.Push(global_arena->RawNew<LValAction>(e1));
         act->IncrementPos();
       } else if (act->Pos() !=
                  static_cast<int>(cast<TupleLiteral>(*exp).Fields().size())) {
@@ -485,7 +486,7 @@ void StepLvalue() {
         // H}
         const Expression* elt =
             cast<TupleLiteral>(*exp).Fields()[act->Pos()].expression;
-        frame->todo.Push(global_arena->New<LValAction>(elt));
+        frame->todo.Push(global_arena->RawNew<LValAction>(elt));
         act->IncrementPos();
       } else {
         CreateTuple(frame, act, exp);
@@ -523,11 +524,11 @@ void StepExp() {
       if (act->Pos() == 0) {
         //    { { e[i] :: C, E, F} :: S, H}
         // -> { { e :: [][i] :: C, E, F} :: S, H}
-        frame->todo.Push(global_arena->New<ExpressionAction>(
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(
             cast<IndexExpression>(*exp).Aggregate()));
         act->IncrementPos();
       } else if (act->Pos() == 1) {
-        frame->todo.Push(global_arena->New<ExpressionAction>(
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(
             cast<IndexExpression>(*exp).Offset()));
         act->IncrementPos();
       } else if (act->Pos() == 2) {
@@ -544,7 +545,7 @@ void StepExp() {
                   << "field " << f << " not in " << *tuple;
             }
             frame->todo.Pop(1);
-            frame->todo.Push(global_arena->New<ValAction>(field));
+            frame->todo.Push(global_arena->RawNew<ValAction>(field));
             break;
           }
           default:
@@ -561,7 +562,7 @@ void StepExp() {
           // -> { {e1 :: (f1=[],...) :: C, E, F} :: S, H}
           const Expression* e1 =
               cast<TupleLiteral>(*exp).Fields()[0].expression;
-          frame->todo.Push(global_arena->New<ExpressionAction>(e1));
+          frame->todo.Push(global_arena->RawNew<ExpressionAction>(e1));
           act->IncrementPos();
         } else {
           CreateTuple(frame, act, exp);
@@ -574,7 +575,7 @@ void StepExp() {
         // H}
         const Expression* elt =
             cast<TupleLiteral>(*exp).Fields()[act->Pos()].expression;
-        frame->todo.Push(global_arena->New<ExpressionAction>(elt));
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(elt));
         act->IncrementPos();
       } else {
         CreateTuple(frame, act, exp);
@@ -587,7 +588,7 @@ void StepExp() {
         //    { { e.f :: C, E, F} :: S, H}
         // -> { { e :: [].f :: C, E, F} :: S, H}
         frame->todo.Push(
-            global_arena->New<ExpressionAction>(access.Aggregate()));
+            global_arena->RawNew<ExpressionAction>(access.Aggregate()));
         act->IncrementPos();
       } else {
         //    { { v :: [].f :: C, E, F} :: S, H}
@@ -595,7 +596,7 @@ void StepExp() {
         const Value* element = act->Results()[0]->GetField(
             FieldPath(access.Field()), exp->LineNumber());
         frame->todo.Pop(1);
-        frame->todo.Push(global_arena->New<ValAction>(element));
+        frame->todo.Push(global_arena->RawNew<ValAction>(element));
       }
       break;
     }
@@ -606,22 +607,22 @@ void StepExp() {
       Address pointer = GetFromEnv(exp->LineNumber(), ident.Name());
       const Value* pointee = state->heap.Read(pointer, exp->LineNumber());
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ValAction>(pointee));
+      frame->todo.Push(global_arena->RawNew<ValAction>(pointee));
       break;
     }
     case Expression::Kind::IntLiteral:
       CHECK(act->Pos() == 0);
       // { {n :: C, E, F} :: S, H} -> { {n' :: C, E, F} :: S, H}
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ValAction>(
-          global_arena->New<IntValue>(cast<IntLiteral>(*exp).Val())));
+      frame->todo.Push(global_arena->RawNew<ValAction>(
+          global_arena->RawNew<IntValue>(cast<IntLiteral>(*exp).Val())));
       break;
     case Expression::Kind::BoolLiteral:
       CHECK(act->Pos() == 0);
       // { {n :: C, E, F} :: S, H} -> { {n' :: C, E, F} :: S, H}
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ValAction>(
-          global_arena->New<BoolValue>(cast<BoolLiteral>(*exp).Val())));
+      frame->todo.Push(global_arena->RawNew<ValAction>(
+          global_arena->RawNew<BoolValue>(cast<BoolLiteral>(*exp).Val())));
       break;
     case Expression::Kind::PrimitiveOperatorExpression: {
       const auto& op = cast<PrimitiveOperatorExpression>(*exp);
@@ -629,14 +630,14 @@ void StepExp() {
         //    { {v :: op(vs,[],e,es) :: C, E, F} :: S, H}
         // -> { {e :: op(vs,v,[],es) :: C, E, F} :: S, H}
         const Expression* arg = op.Arguments()[act->Pos()];
-        frame->todo.Push(global_arena->New<ExpressionAction>(arg));
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(arg));
         act->IncrementPos();
       } else {
         //    { {v :: op(vs,[]) :: C, E, F} :: S, H}
         // -> { {eval_prim(op, (vs,v)) :: C, E, F} :: S, H}
         const Value* v = EvalPrim(op.Op(), act->Results(), exp->LineNumber());
         frame->todo.Pop(1);
-        frame->todo.Push(global_arena->New<ValAction>(v));
+        frame->todo.Push(global_arena->RawNew<ValAction>(v));
       }
       break;
     }
@@ -644,13 +645,13 @@ void StepExp() {
       if (act->Pos() == 0) {
         //    { {e1(e2) :: C, E, F} :: S, H}
         // -> { {e1 :: [](e2) :: C, E, F} :: S, H}
-        frame->todo.Push(global_arena->New<ExpressionAction>(
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(
             cast<CallExpression>(*exp).Function()));
         act->IncrementPos();
       } else if (act->Pos() == 1) {
         //    { { v :: [](e) :: C, E, F} :: S, H}
         // -> { { e :: v([]) :: C, E, F} :: S, H}
-        frame->todo.Push(global_arena->New<ExpressionAction>(
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(
             cast<CallExpression>(*exp).Argument()));
         act->IncrementPos();
       } else if (act->Pos() == 2) {
@@ -673,73 +674,74 @@ void StepExp() {
           CHECK(pointee->Tag() == Value::Kind::StringValue);
           // TODO: This could eventually use something like llvm::formatv.
           llvm::outs() << cast<StringValue>(*pointee).Val();
-          frame->todo.Push(global_arena->New<ValAction>(&TupleValue::Empty()));
+          frame->todo.Push(
+              global_arena->RawNew<ValAction>(&TupleValue::Empty()));
           break;
       }
       break;
 
     case Expression::Kind::IntTypeLiteral: {
       CHECK(act->Pos() == 0);
-      const Value* v = global_arena->New<IntType>();
+      const Value* v = global_arena->RawNew<IntType>();
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ValAction>(v));
+      frame->todo.Push(global_arena->RawNew<ValAction>(v));
       break;
     }
     case Expression::Kind::BoolTypeLiteral: {
       CHECK(act->Pos() == 0);
-      const Value* v = global_arena->New<BoolType>();
+      const Value* v = global_arena->RawNew<BoolType>();
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ValAction>(v));
+      frame->todo.Push(global_arena->RawNew<ValAction>(v));
       break;
     }
     case Expression::Kind::TypeTypeLiteral: {
       CHECK(act->Pos() == 0);
-      const Value* v = global_arena->New<TypeType>();
+      const Value* v = global_arena->RawNew<TypeType>();
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ValAction>(v));
+      frame->todo.Push(global_arena->RawNew<ValAction>(v));
       break;
     }
     case Expression::Kind::FunctionTypeLiteral: {
       if (act->Pos() == 0) {
-        frame->todo.Push(global_arena->New<ExpressionAction>(
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(
             cast<FunctionTypeLiteral>(*exp).Parameter()));
         act->IncrementPos();
       } else if (act->Pos() == 1) {
         //    { { pt :: fn [] -> e :: C, E, F} :: S, H}
         // -> { { e :: fn pt -> []) :: C, E, F} :: S, H}
-        frame->todo.Push(global_arena->New<ExpressionAction>(
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(
             cast<FunctionTypeLiteral>(*exp).ReturnType()));
         act->IncrementPos();
       } else if (act->Pos() == 2) {
         //    { { rt :: fn pt -> [] :: C, E, F} :: S, H}
         // -> { fn pt -> rt :: {C, E, F} :: S, H}
-        const Value* v = global_arena->New<FunctionType>(
+        const Value* v = global_arena->RawNew<FunctionType>(
             std::vector<GenericBinding>(), act->Results()[0],
             act->Results()[1]);
         frame->todo.Pop(1);
-        frame->todo.Push(global_arena->New<ValAction>(v));
+        frame->todo.Push(global_arena->RawNew<ValAction>(v));
       }
       break;
     }
     case Expression::Kind::ContinuationTypeLiteral: {
       CHECK(act->Pos() == 0);
-      const Value* v = global_arena->New<ContinuationType>();
+      const Value* v = global_arena->RawNew<ContinuationType>();
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ValAction>(v));
+      frame->todo.Push(global_arena->RawNew<ValAction>(v));
       break;
     }
     case Expression::Kind::StringLiteral:
       CHECK(act->Pos() == 0);
       // { {n :: C, E, F} :: S, H} -> { {n' :: C, E, F} :: S, H}
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ValAction>(
-          global_arena->New<StringValue>(cast<StringLiteral>(*exp).Val())));
+      frame->todo.Push(global_arena->RawNew<ValAction>(
+          global_arena->RawNew<StringValue>(cast<StringLiteral>(*exp).Val())));
       break;
     case Expression::Kind::StringTypeLiteral: {
       CHECK(act->Pos() == 0);
-      const Value* v = global_arena->New<StringType>();
+      const Value* v = global_arena->RawNew<StringType>();
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ValAction>(v));
+      frame->todo.Push(global_arena->RawNew<ValAction>(v));
       break;
     }
   }  // switch (exp->Tag)
@@ -755,21 +757,21 @@ void StepPattern() {
   switch (pattern->Tag()) {
     case Pattern::Kind::AutoPattern: {
       CHECK(act->Pos() == 0);
-      const Value* v = global_arena->New<AutoType>();
+      const Value* v = global_arena->RawNew<AutoType>();
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ValAction>(v));
+      frame->todo.Push(global_arena->RawNew<ValAction>(v));
       break;
     }
     case Pattern::Kind::BindingPattern: {
       const auto& binding = cast<BindingPattern>(*pattern);
       if (act->Pos() == 0) {
-        frame->todo.Push(global_arena->New<PatternAction>(binding.Type()));
+        frame->todo.Push(global_arena->RawNew<PatternAction>(binding.Type()));
         act->IncrementPos();
       } else {
-        auto v = global_arena->New<BindingPlaceholderValue>(binding.Name(),
-                                                            act->Results()[0]);
+        auto v = global_arena->RawNew<BindingPlaceholderValue>(
+            binding.Name(), act->Results()[0]);
         frame->todo.Pop(1);
-        frame->todo.Push(global_arena->New<ValAction>(v));
+        frame->todo.Push(global_arena->RawNew<ValAction>(v));
       }
       break;
     }
@@ -778,10 +780,11 @@ void StepPattern() {
       if (act->Pos() == 0) {
         if (tuple.Fields().empty()) {
           frame->todo.Pop(1);
-          frame->todo.Push(global_arena->New<ValAction>(&TupleValue::Empty()));
+          frame->todo.Push(
+              global_arena->RawNew<ValAction>(&TupleValue::Empty()));
         } else {
           const Pattern* p1 = tuple.Fields()[0].pattern;
-          frame->todo.Push(global_arena->New<PatternAction>(p1));
+          frame->todo.Push(global_arena->RawNew<PatternAction>(p1));
           act->IncrementPos();
         }
       } else if (act->Pos() != static_cast<int>(tuple.Fields().size())) {
@@ -790,7 +793,7 @@ void StepPattern() {
         // -> { { ek+1 :: (f1=v1,..., fk=vk, fk+1=[],...) :: C, E, F} :: S,
         // H}
         const Pattern* elt = tuple.Fields()[act->Pos()].pattern;
-        frame->todo.Push(global_arena->New<PatternAction>(elt));
+        frame->todo.Push(global_arena->RawNew<PatternAction>(elt));
         act->IncrementPos();
       } else {
         std::vector<TupleElement> elements;
@@ -799,9 +802,9 @@ void StepPattern() {
               {.name = tuple.Fields()[i].name, .value = act->Results()[i]});
         }
         const Value* tuple_value =
-            global_arena->New<TupleValue>(std::move(elements));
+            global_arena->RawNew<TupleValue>(std::move(elements));
         frame->todo.Pop(1);
-        frame->todo.Push(global_arena->New<ValAction>(tuple_value));
+        frame->todo.Push(global_arena->RawNew<ValAction>(tuple_value));
       }
       break;
     }
@@ -809,18 +812,18 @@ void StepPattern() {
       const auto& alternative = cast<AlternativePattern>(*pattern);
       if (act->Pos() == 0) {
         frame->todo.Push(
-            global_arena->New<ExpressionAction>(alternative.ChoiceType()));
+            global_arena->RawNew<ExpressionAction>(alternative.ChoiceType()));
         act->IncrementPos();
       } else if (act->Pos() == 1) {
         frame->todo.Push(
-            global_arena->New<PatternAction>(alternative.Arguments()));
+            global_arena->RawNew<PatternAction>(alternative.Arguments()));
         act->IncrementPos();
       } else {
         CHECK(act->Pos() == 2);
         const auto& choice_type = cast<ChoiceType>(*act->Results()[0]);
         frame->todo.Pop(1);
-        frame->todo.Push(
-            global_arena->New<ValAction>(global_arena->New<AlternativeValue>(
+        frame->todo.Push(global_arena->RawNew<ValAction>(
+            global_arena->RawNew<AlternativeValue>(
                 alternative.AlternativeName(), choice_type.Name(),
                 act->Results()[1])));
       }
@@ -828,7 +831,7 @@ void StepPattern() {
     }
     case Pattern::Kind::ExpressionPattern:
       frame->todo.Pop(1);
-      frame->todo.Push(global_arena->New<ExpressionAction>(
+      frame->todo.Push(global_arena->RawNew<ExpressionAction>(
           cast<ExpressionPattern>(pattern)->Expression()));
       break;
   }
@@ -880,7 +883,7 @@ void StepStmt() {
         //    { { (match (e) ...) :: C, E, F} :: S, H}
         // -> { { e :: (match ([]) ...) :: C, E, F} :: S, H}
         frame->todo.Push(
-            global_arena->New<ExpressionAction>(cast<Match>(*stmt).Exp()));
+            global_arena->RawNew<ExpressionAction>(cast<Match>(*stmt).Exp()));
         act->IncrementPos();
       } else {
         // Regarding act->Pos():
@@ -905,7 +908,7 @@ void StepStmt() {
           // start interpreting the pattern of the clause
           //    { {v :: (match ([]) ...) :: C, E, F} :: S, H}
           // -> { {pi :: (match ([]) ...) :: C, E, F} :: S, H}
-          frame->todo.Push(global_arena->New<PatternAction>(c->first));
+          frame->todo.Push(global_arena->RawNew<PatternAction>(c->first));
           act->IncrementPos();
         } else {  // try to match
           auto v = act->Results()[0];
@@ -915,15 +918,16 @@ void StepStmt() {
           std::optional<Env> matches =
               PatternMatch(pat, v, values, &vars, stmt->LineNumber());
           if (matches) {  // we have a match, start the body
-            auto* new_scope = global_arena->New<Scope>(*matches, vars);
+            auto* new_scope = global_arena->RawNew<Scope>(*matches, vars);
             frame->scopes.Push(new_scope);
             const Statement* body_block =
-                global_arena->New<Block>(stmt->LineNumber(), c->second);
-            Action* body_act = global_arena->New<StatementAction>(body_block);
+                global_arena->RawNew<Block>(stmt->LineNumber(), c->second);
+            Action* body_act =
+                global_arena->RawNew<StatementAction>(body_block);
             body_act->IncrementPos();
             frame->todo.Pop(1);
             frame->todo.Push(body_act);
-            frame->todo.Push(global_arena->New<StatementAction>(c->second));
+            frame->todo.Push(global_arena->RawNew<StatementAction>(c->second));
           } else {
             // this case did not match, moving on
             act->IncrementPos();
@@ -941,14 +945,14 @@ void StepStmt() {
         //    { { (while (e) s) :: C, E, F} :: S, H}
         // -> { { e :: (while ([]) s) :: C, E, F} :: S, H}
         frame->todo.Push(
-            global_arena->New<ExpressionAction>(cast<While>(*stmt).Cond()));
+            global_arena->RawNew<ExpressionAction>(cast<While>(*stmt).Cond()));
         act->IncrementPos();
       } else if (cast<BoolValue>(*act->Results()[0]).Val()) {
         //    { {true :: (while ([]) s) :: C, E, F} :: S, H}
         // -> { { s :: (while (e) s) :: C, E, F } :: S, H}
         frame->todo.Top()->Clear();
         frame->todo.Push(
-            global_arena->New<StatementAction>(cast<While>(*stmt).Body()));
+            global_arena->RawNew<StatementAction>(cast<While>(*stmt).Body()));
       } else {
         //    { {false :: (while ([]) s) :: C, E, F} :: S, H}
         // -> { { C, E, F } :: S, H}
@@ -986,11 +990,11 @@ void StepStmt() {
     case Statement::Kind::Block: {
       if (act->Pos() == 0) {
         if (cast<Block>(*stmt).Stmt()) {
-          auto* scope = global_arena->New<Scope>(CurrentEnv(state),
-                                                 std::list<std::string>());
+          auto* scope = global_arena->RawNew<Scope>(CurrentEnv(state),
+                                                    std::list<std::string>());
           frame->scopes.Push(scope);
           frame->todo.Push(
-              global_arena->New<StatementAction>(cast<Block>(*stmt).Stmt()));
+              global_arena->RawNew<StatementAction>(cast<Block>(*stmt).Stmt()));
           act->IncrementPos();
           act->IncrementPos();
         } else {
@@ -1008,11 +1012,11 @@ void StepStmt() {
       if (act->Pos() == 0) {
         //    { {(var x = e) :: C, E, F} :: S, H}
         // -> { {e :: (var x = []) :: C, E, F} :: S, H}
-        frame->todo.Push(global_arena->New<ExpressionAction>(
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(
             cast<VariableDefinition>(*stmt).Init()));
         act->IncrementPos();
       } else if (act->Pos() == 1) {
-        frame->todo.Push(global_arena->New<PatternAction>(
+        frame->todo.Push(global_arena->RawNew<PatternAction>(
             cast<VariableDefinition>(*stmt).Pat()));
         act->IncrementPos();
       } else if (act->Pos() == 2) {
@@ -1035,7 +1039,7 @@ void StepStmt() {
       if (act->Pos() == 0) {
         //    { {e :: C, E, F} :: S, H}
         // -> { {e :: C, E, F} :: S, H}
-        frame->todo.Push(global_arena->New<ExpressionAction>(
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(
             cast<ExpressionStatement>(*stmt).Exp()));
         act->IncrementPos();
       } else {
@@ -1047,13 +1051,13 @@ void StepStmt() {
         //    { {(lv = e) :: C, E, F} :: S, H}
         // -> { {lv :: ([] = e) :: C, E, F} :: S, H}
         frame->todo.Push(
-            global_arena->New<LValAction>(cast<Assign>(*stmt).Lhs()));
+            global_arena->RawNew<LValAction>(cast<Assign>(*stmt).Lhs()));
         act->IncrementPos();
       } else if (act->Pos() == 1) {
         //    { { a :: ([] = e) :: C, E, F} :: S, H}
         // -> { { e :: (a = []) :: C, E, F} :: S, H}
         frame->todo.Push(
-            global_arena->New<ExpressionAction>(cast<Assign>(*stmt).Rhs()));
+            global_arena->RawNew<ExpressionAction>(cast<Assign>(*stmt).Rhs()));
         act->IncrementPos();
       } else if (act->Pos() == 2) {
         //    { { v :: (a = []) :: C, E, F} :: S, H}
@@ -1069,7 +1073,7 @@ void StepStmt() {
         //    { {(if (e) then_stmt else else_stmt) :: C, E, F} :: S, H}
         // -> { { e :: (if ([]) then_stmt else else_stmt) :: C, E, F} :: S, H}
         frame->todo.Push(
-            global_arena->New<ExpressionAction>(cast<If>(*stmt).Cond()));
+            global_arena->RawNew<ExpressionAction>(cast<If>(*stmt).Cond()));
         act->IncrementPos();
       } else if (cast<BoolValue>(*act->Results()[0]).Val()) {
         //    { {true :: if ([]) then_stmt else else_stmt :: C, E, F} ::
@@ -1077,14 +1081,14 @@ void StepStmt() {
         // -> { { then_stmt :: C, E, F } :: S, H}
         frame->todo.Pop(1);
         frame->todo.Push(
-            global_arena->New<StatementAction>(cast<If>(*stmt).ThenStmt()));
+            global_arena->RawNew<StatementAction>(cast<If>(*stmt).ThenStmt()));
       } else if (cast<If>(*stmt).ElseStmt()) {
         //    { {false :: if ([]) then_stmt else else_stmt :: C, E, F} ::
         //      S, H}
         // -> { { else_stmt :: C, E, F } :: S, H}
         frame->todo.Pop(1);
         frame->todo.Push(
-            global_arena->New<StatementAction>(cast<If>(*stmt).ElseStmt()));
+            global_arena->RawNew<StatementAction>(cast<If>(*stmt).ElseStmt()));
       } else {
         frame->todo.Pop(1);
       }
@@ -1094,7 +1098,7 @@ void StepStmt() {
         //    { {return e :: C, E, F} :: S, H}
         // -> { {e :: return [] :: C, E, F} :: S, H}
         frame->todo.Push(
-            global_arena->New<ExpressionAction>(cast<Return>(*stmt).Exp()));
+            global_arena->RawNew<ExpressionAction>(cast<Return>(*stmt).Exp()));
         act->IncrementPos();
       } else {
         //    { {v :: return [] :: C, E, F} :: {C', E', F'} :: S, H}
@@ -1103,7 +1107,7 @@ void StepStmt() {
         DeallocateLocals(stmt->LineNumber(), frame);
         state->stack.Pop(1);
         frame = state->stack.Top();
-        frame->todo.Push(global_arena->New<ValAction>(ret_val));
+        frame->todo.Push(global_arena->RawNew<ValAction>(ret_val));
       }
       break;
     case Statement::Kind::Sequence:
@@ -1112,30 +1116,30 @@ void StepStmt() {
       // -> { { s1 :: s2 :: C, E, F} :: S, H}
       frame->todo.Pop(1);
       if (cast<Sequence>(*stmt).Next()) {
-        frame->todo.Push(
-            global_arena->New<StatementAction>(cast<Sequence>(*stmt).Next()));
+        frame->todo.Push(global_arena->RawNew<StatementAction>(
+            cast<Sequence>(*stmt).Next()));
       }
       frame->todo.Push(
-          global_arena->New<StatementAction>(cast<Sequence>(*stmt).Stmt()));
+          global_arena->RawNew<StatementAction>(cast<Sequence>(*stmt).Stmt()));
       break;
     case Statement::Kind::Continuation: {
       CHECK(act->Pos() == 0);
       // Create a continuation object by creating a frame similar the
       // way one is created in a function call.
-      Scope* scope =
-          global_arena->New<Scope>(CurrentEnv(state), std::list<std::string>());
+      Scope* scope = global_arena->RawNew<Scope>(CurrentEnv(state),
+                                                 std::list<std::string>());
       Stack<Scope*> scopes;
       scopes.Push(scope);
       Stack<Action*> todo;
-      todo.Push(global_arena->New<StatementAction>(
-          global_arena->New<Return>(stmt->LineNumber(), nullptr,
-                                    /*is_omitted_exp=*/true)));
-      todo.Push(
-          global_arena->New<StatementAction>(cast<Continuation>(*stmt).Body()));
+      todo.Push(global_arena->RawNew<StatementAction>(
+          global_arena->RawNew<Return>(stmt->LineNumber(), nullptr,
+                                       /*is_omitted_exp=*/true)));
+      todo.Push(global_arena->RawNew<StatementAction>(
+          cast<Continuation>(*stmt).Body()));
       Frame* continuation_frame =
-          global_arena->New<Frame>("__continuation", scopes, todo);
+          global_arena->RawNew<Frame>("__continuation", scopes, todo);
       Address continuation_address =
-          state->heap.AllocateValue(global_arena->New<ContinuationValue>(
+          state->heap.AllocateValue(global_arena->RawNew<ContinuationValue>(
               std::vector<Frame*>({continuation_frame})));
       // Store the continuation's address in the frame.
       continuation_frame->continuation = continuation_address;
@@ -1150,17 +1154,17 @@ void StepStmt() {
     case Statement::Kind::Run:
       if (act->Pos() == 0) {
         // Evaluate the argument of the run statement.
-        frame->todo.Push(
-            global_arena->New<ExpressionAction>(cast<Run>(*stmt).Argument()));
+        frame->todo.Push(global_arena->RawNew<ExpressionAction>(
+            cast<Run>(*stmt).Argument()));
         act->IncrementPos();
       } else {
         frame->todo.Pop(1);
         // Push an expression statement action to ignore the result
         // value from the continuation.
-        Action* ignore_result = global_arena->New<StatementAction>(
-            global_arena->New<ExpressionStatement>(
+        Action* ignore_result = global_arena->RawNew<StatementAction>(
+            global_arena->RawNew<ExpressionStatement>(
                 stmt->LineNumber(),
-                global_arena->New<TupleLiteral>(stmt->LineNumber())));
+                global_arena->RawNew<TupleLiteral>(stmt->LineNumber())));
         frame->todo.Push(ignore_result);
         // Push the continuation onto the current stack.
         const std::vector<Frame*>& continuation_vector =
@@ -1181,7 +1185,7 @@ void StepStmt() {
       } while (paused.back()->continuation == std::nullopt);
       // Update the continuation with the paused stack.
       state->heap.Write(*paused.back()->continuation,
-                        global_arena->New<ContinuationValue>(paused),
+                        global_arena->RawNew<ContinuationValue>(paused),
                         stmt->LineNumber());
       break;
   }
@@ -1220,18 +1224,18 @@ void Step() {
 
 // Interpret the whole porogram.
 auto InterpProgram(const std::list<const Declaration*>& fs) -> int {
-  state = global_arena->New<State>();  // Runtime state.
+  state = global_arena->RawNew<State>();  // Runtime state.
   if (tracing_output) {
     llvm::outs() << "********** initializing globals **********\n";
   }
   InitGlobals(fs);
 
-  const Expression* arg = global_arena->New<TupleLiteral>(0);
-  const Expression* call_main = global_arena->New<CallExpression>(
-      0, global_arena->New<IdentifierExpression>(0, "main"), arg);
-  auto todo = Stack<Action*>(global_arena->New<ExpressionAction>(call_main));
-  auto* scope = global_arena->New<Scope>(globals, std::list<std::string>());
-  auto* frame = global_arena->New<Frame>("top", Stack(scope), todo);
+  const Expression* arg = global_arena->RawNew<TupleLiteral>(0);
+  const Expression* call_main = global_arena->RawNew<CallExpression>(
+      0, global_arena->RawNew<IdentifierExpression>(0, "main"), arg);
+  auto todo = Stack<Action*>(global_arena->RawNew<ExpressionAction>(call_main));
+  auto* scope = global_arena->RawNew<Scope>(globals, std::list<std::string>());
+  auto* frame = global_arena->RawNew<Frame>("top", Stack(scope), todo);
   state->stack = Stack(frame);
 
   if (tracing_output) {
@@ -1252,9 +1256,9 @@ auto InterpProgram(const std::list<const Declaration*>& fs) -> int {
 
 // Interpret an expression at compile-time.
 auto InterpExp(Env values, const Expression* e) -> const Value* {
-  auto todo = Stack<Action*>(global_arena->New<ExpressionAction>(e));
-  auto* scope = global_arena->New<Scope>(values, std::list<std::string>());
-  auto* frame = global_arena->New<Frame>("InterpExp", Stack(scope), todo);
+  auto todo = Stack<Action*>(global_arena->RawNew<ExpressionAction>(e));
+  auto* scope = global_arena->RawNew<Scope>(values, std::list<std::string>());
+  auto* frame = global_arena->RawNew<Frame>("InterpExp", Stack(scope), todo);
   state->stack = Stack(frame);
 
   while (state->stack.Count() > 1 || state->stack.Top()->todo.Count() > 1 ||
@@ -1266,9 +1270,10 @@ auto InterpExp(Env values, const Expression* e) -> const Value* {
 
 // Interpret a pattern at compile-time.
 auto InterpPattern(Env values, const Pattern* p) -> const Value* {
-  auto todo = Stack<Action*>(global_arena->New<PatternAction>(p));
-  auto* scope = global_arena->New<Scope>(values, std::list<std::string>());
-  auto* frame = global_arena->New<Frame>("InterpPattern", Stack(scope), todo);
+  auto todo = Stack<Action*>(global_arena->RawNew<PatternAction>(p));
+  auto* scope = global_arena->RawNew<Scope>(values, std::list<std::string>());
+  auto* frame =
+      global_arena->RawNew<Frame>("InterpPattern", Stack(scope), todo);
   state->stack = Stack(frame);
 
   while (state->stack.Count() > 1 || state->stack.Top()->todo.Count() > 1 ||
diff --git a/executable_semantics/interpreter/typecheck.cpp b/executable_semantics/interpreter/typecheck.cpp
index aa1684005075..ed3a9ebbe2cb 100644
--- a/executable_semantics/interpreter/typecheck.cpp
+++ b/executable_semantics/interpreter/typecheck.cpp
@@ -46,16 +46,16 @@ static void ExpectPointerType(int line_num, const std::string& context,
 static auto ReifyType(const Value* t, int line_num) -> const Expression* {
   switch (t->Tag()) {
     case Value::Kind::IntType:
-      return global_arena->New<IntTypeLiteral>(0);
+      return global_arena->RawNew<IntTypeLiteral>(0);
     case Value::Kind::BoolType:
-      return global_arena->New<BoolTypeLiteral>(0);
+      return global_arena->RawNew<BoolTypeLiteral>(0);
     case Value::Kind::TypeType:
-      return global_arena->New<TypeTypeLiteral>(0);
+      return global_arena->RawNew<TypeTypeLiteral>(0);
     case Value::Kind::ContinuationType:
-      return global_arena->New<ContinuationTypeLiteral>(0);
+      return global_arena->RawNew<ContinuationTypeLiteral>(0);
     case Value::Kind::FunctionType: {
       const auto& fn_type = cast<FunctionType>(*t);
-      return global_arena->New<FunctionTypeLiteral>(
+      return global_arena->RawNew<FunctionTypeLiteral>(
           0, ReifyType(fn_type.Param(), line_num),
           ReifyType(fn_type.Ret(), line_num),
           /*is_omitted_return_type=*/false);
@@ -66,24 +66,24 @@ static auto ReifyType(const Value* t, int line_num) -> const Expression* {
         args.push_back(
             FieldInitializer(field.name, ReifyType(field.value, line_num)));
       }
-      return global_arena->New<TupleLiteral>(0, args);
+      return global_arena->RawNew<TupleLiteral>(0, args);
     }
     case Value::Kind::StructType:
-      return global_arena->New<IdentifierExpression>(
+      return global_arena->RawNew<IdentifierExpression>(
           0, cast<StructType>(*t).Name());
     case Value::Kind::ChoiceType:
-      return global_arena->New<IdentifierExpression>(
+      return global_arena->RawNew<IdentifierExpression>(
           0, cast<ChoiceType>(*t).Name());
     case Value::Kind::PointerType:
-      return global_arena->New<PrimitiveOperatorExpression>(
+      return global_arena->RawNew<PrimitiveOperatorExpression>(
           0, Operator::Ptr,
           std::vector<const Expression*>(
               {ReifyType(cast<PointerType>(*t).Type(), line_num)}));
     case Value::Kind::VariableType:
-      return global_arena->New<IdentifierExpression>(
+      return global_arena->RawNew<IdentifierExpression>(
           0, cast<VariableType>(*t).Name());
     case Value::Kind::StringType:
-      return global_arena->New<StringTypeLiteral>(0);
+      return global_arena->RawNew<StringTypeLiteral>(0);
     case Value::Kind::AlternativeConstructorValue:
     case Value::Kind::AlternativeValue:
     case Value::Kind::AutoType:
@@ -206,17 +206,17 @@ static auto Substitute(TypeEnv dict, const Value* type) -> const Value* {
         auto t = Substitute(dict, elt.value);
         elts.push_back({.name = elt.name, .value = t});
       }
-      return global_arena->New<TupleValue>(elts);
+      return global_arena->RawNew<TupleValue>(elts);
     }
     case Value::Kind::FunctionType: {
       const auto& fn_type = cast<FunctionType>(*type);
       auto param = Substitute(dict, fn_type.Param());
       auto ret = Substitute(dict, fn_type.Ret());
-      return global_arena->New<FunctionType>(std::vector<GenericBinding>(),
-                                             param, ret);
+      return global_arena->RawNew<FunctionType>(std::vector<GenericBinding>(),
+                                                param, ret);
     }
     case Value::Kind::PointerType: {
-      return global_arena->New<PointerType>(
+      return global_arena->RawNew<PointerType>(
           Substitute(dict, cast<PointerType>(*type).Type()));
     }
     case Value::Kind::AutoType:
@@ -275,9 +275,9 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
             FATAL_COMPILATION_ERROR(e->LineNumber())
                 << "field " << f << " is not in the tuple " << *t;
           }
-          auto new_e = global_arena->New<IndexExpression>(
+          auto new_e = global_arena->RawNew<IndexExpression>(
               e->LineNumber(), res.exp,
-              global_arena->New<IntLiteral>(e->LineNumber(), i));
+              global_arena->RawNew<IntLiteral>(e->LineNumber(), i));
           return TCExpression(new_e, field_t, res.types);
         }
         default:
@@ -294,8 +294,9 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
         new_args.push_back(FieldInitializer(arg.name, arg_res.exp));
         arg_types.push_back({.name = arg.name, .value = arg_res.type});
       }
-      auto tuple_e = global_arena->New<TupleLiteral>(e->LineNumber(), new_args);
-      auto tuple_t = global_arena->New<TupleValue>(std::move(arg_types));
+      auto tuple_e =
+          global_arena->RawNew<TupleLiteral>(e->LineNumber(), new_args);
+      auto tuple_t = global_arena->RawNew<TupleValue>(std::move(arg_types));
       return TCExpression(tuple_e, tuple_t, new_types);
     }
     case Expression::Kind::FieldAccessExpression: {
@@ -309,7 +310,7 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
           for (auto& field : t_struct.Fields()) {
             if (access.Field() == field.first) {
               const Expression* new_e =
-                  global_arena->New<FieldAccessExpression>(
+                  global_arena->RawNew<FieldAccessExpression>(
                       e->LineNumber(), res.exp, access.Field());
               return TCExpression(new_e, field.second, res.types);
             }
@@ -318,7 +319,7 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
           for (auto& method : t_struct.Methods()) {
             if (access.Field() == method.first) {
               const Expression* new_e =
-                  global_arena->New<FieldAccessExpression>(
+                  global_arena->RawNew<FieldAccessExpression>(
                       e->LineNumber(), res.exp, access.Field());
               return TCExpression(new_e, method.second, res.types);
             }
@@ -331,7 +332,7 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
           const auto& tup = cast<TupleValue>(*t);
           for (const TupleElement& field : tup.Elements()) {
             if (access.Field() == field.name) {
-              auto new_e = global_arena->New<FieldAccessExpression>(
+              auto new_e = global_arena->RawNew<FieldAccessExpression>(
                   e->LineNumber(), res.exp, access.Field());
               return TCExpression(new_e, field.value, res.types);
             }
@@ -345,9 +346,9 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
           for (const auto& vt : choice.Alternatives()) {
             if (access.Field() == vt.first) {
               const Expression* new_e =
-                  global_arena->New<FieldAccessExpression>(
+                  global_arena->RawNew<FieldAccessExpression>(
                       e->LineNumber(), res.exp, access.Field());
-              auto fun_ty = global_arena->New<FunctionType>(
+              auto fun_ty = global_arena->RawNew<FunctionType>(
                   std::vector<GenericBinding>(), vt.second, t);
               return TCExpression(new_e, fun_ty, res.types);
             }
@@ -373,9 +374,9 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
       }
     }
     case Expression::Kind::IntLiteral:
-      return TCExpression(e, global_arena->New<IntType>(), types);
+      return TCExpression(e, global_arena->RawNew<IntType>(), types);
     case Expression::Kind::BoolLiteral:
-      return TCExpression(e, global_arena->New<BoolType>(), types);
+      return TCExpression(e, global_arena->RawNew<BoolType>(), types);
     case Expression::Kind::PrimitiveOperatorExpression: {
       const auto& op = cast<PrimitiveOperatorExpression>(*e);
       std::vector<const Expression*> es;
@@ -387,58 +388,67 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
         es.push_back(res.exp);
         ts.push_back(res.type);
       }
-      auto new_e = global_arena->New<PrimitiveOperatorExpression>(
+      auto new_e = global_arena->RawNew<PrimitiveOperatorExpression>(
           e->LineNumber(), op.Op(), es);
       switch (op.Op()) {
         case Operator::Neg:
-          ExpectType(e->LineNumber(), "negation", global_arena->New<IntType>(),
-                     ts[0]);
-          return TCExpression(new_e, global_arena->New<IntType>(), new_types);
+          ExpectType(e->LineNumber(), "negation",
+                     global_arena->RawNew<IntType>(), ts[0]);
+          return TCExpression(new_e, global_arena->RawNew<IntType>(),
+                              new_types);
         case Operator::Add:
           ExpectType(e->LineNumber(), "addition(1)",
-                     global_arena->New<IntType>(), ts[0]);
+                     global_arena->RawNew<IntType>(), ts[0]);
           ExpectType(e->LineNumber(), "addition(2)",
-                     global_arena->New<IntType>(), ts[1]);
-          return TCExpression(new_e, global_arena->New<IntType>(), new_types);
+                     global_arena->RawNew<IntType>(), ts[1]);
+          return TCExpression(new_e, global_arena->RawNew<IntType>(),
+                              new_types);
         case Operator::Sub:
           ExpectType(e->LineNumber(), "subtraction(1)",
-                     global_arena->New<IntType>(), ts[0]);
+                     global_arena->RawNew<IntType>(), ts[0]);
           ExpectType(e->LineNumber(), "subtraction(2)",
-                     global_arena->New<IntType>(), ts[1]);
-          return TCExpression(new_e, global_arena->New<IntType>(), new_types);
+                     global_arena->RawNew<IntType>(), ts[1]);
+          return TCExpression(new_e, global_arena->RawNew<IntType>(),
+                              new_types);
         case Operator::Mul:
           ExpectType(e->LineNumber(), "multiplication(1)",
-                     global_arena->New<IntType>(), ts[0]);
+                     global_arena->RawNew<IntType>(), ts[0]);
           ExpectType(e->LineNumber(), "multiplication(2)",
-                     global_arena->New<IntType>(), ts[1]);
-          return TCExpression(new_e, global_arena->New<IntType>(), new_types);
+                     global_arena->RawNew<IntType>(), ts[1]);
+          return TCExpression(new_e, global_arena->RawNew<IntType>(),
+                              new_types);
         case Operator::And:
-          ExpectType(e->LineNumber(), "&&(1)", global_arena->New<BoolType>(),
+          ExpectType(e->LineNumber(), "&&(1)", global_arena->RawNew<BoolType>(),
                      ts[0]);
-          ExpectType(e->LineNumber(), "&&(2)", global_arena->New<BoolType>(),
+          ExpectType(e->LineNumber(), "&&(2)", global_arena->RawNew<BoolType>(),
                      ts[1]);
-          return TCExpression(new_e, global_arena->New<BoolType>(), new_types);
+          return TCExpression(new_e, global_arena->RawNew<BoolType>(),
+                              new_types);
         case Operator::Or:
-          ExpectType(e->LineNumber(), "||(1)", global_arena->New<BoolType>(),
+          ExpectType(e->LineNumber(), "||(1)", global_arena->RawNew<BoolType>(),
                      ts[0]);
-          ExpectType(e->LineNumber(), "||(2)", global_arena->New<BoolType>(),
+          ExpectType(e->LineNumber(), "||(2)", global_arena->RawNew<BoolType>(),
                      ts[1]);
-          return TCExpression(new_e, global_arena->New<BoolType>(), new_types);
+          return TCExpression(new_e, global_arena->RawNew<BoolType>(),
+                              new_types);
         case Operator::Not:
-          ExpectType(e->LineNumber(), "!", global_arena->New<BoolType>(),
+          ExpectType(e->LineNumber(), "!", global_arena->RawNew<BoolType>(),
                      ts[0]);
-          return TCExpression(new_e, global_arena->New<BoolType>(), new_types);
+          return TCExpression(new_e, global_arena->RawNew<BoolType>(),
+                              new_types);
         case Operator::Eq:
           ExpectType(e->LineNumber(), "==", ts[0], ts[1]);
-          return TCExpression(new_e, global_arena->New<BoolType>(), new_types);
+          return TCExpression(new_e, global_arena->RawNew<BoolType>(),
+                              new_types);
         case Operator::Deref:
           ExpectPointerType(e->LineNumber(), "*", ts[0]);
           return TCExpression(new_e, cast<PointerType>(*ts[0]).Type(),
                               new_types);
         case Operator::Ptr:
-          ExpectType(e->LineNumber(), "*", global_arena->New<TypeType>(),
+          ExpectType(e->LineNumber(), "*", global_arena->RawNew<TypeType>(),
                      ts[0]);
-          return TCExpression(new_e, global_arena->New<TypeType>(), new_types);
+          return TCExpression(new_e, global_arena->RawNew<TypeType>(),
+                              new_types);
       }
       break;
     }
@@ -468,7 +478,7 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
           } else {
             ExpectType(e->LineNumber(), "call", parameter_type, arg_res.type);
           }
-          auto new_e = global_arena->New<CallExpression>(
+          auto new_e = global_arena->RawNew<CallExpression>(
               e->LineNumber(), fun_res.exp, arg_res.exp);
           return TCExpression(new_e, return_type, arg_res.types);
         }
@@ -484,14 +494,14 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
       const auto& fn = cast<FunctionTypeLiteral>(*e);
       auto pt = InterpExp(values, fn.Parameter());
       auto rt = InterpExp(values, fn.ReturnType());
-      auto new_e = global_arena->New<FunctionTypeLiteral>(
+      auto new_e = global_arena->RawNew<FunctionTypeLiteral>(
           e->LineNumber(), ReifyType(pt, e->LineNumber()),
           ReifyType(rt, e->LineNumber()),
           /*is_omitted_return_type=*/false);
-      return TCExpression(new_e, global_arena->New<TypeType>(), types);
+      return TCExpression(new_e, global_arena->RawNew<TypeType>(), types);
     }
     case Expression::Kind::StringLiteral:
-      return TCExpression(e, global_arena->New<StringType>(), types);
+      return TCExpression(e, global_arena->RawNew<StringType>(), types);
     case Expression::Kind::IntrinsicExpression:
       switch (cast<IntrinsicExpression>(*e).Intrinsic()) {
         case IntrinsicExpression::IntrinsicKind::Print:
@@ -502,7 +512,7 @@ auto TypeCheckExp(const Expression* e, TypeEnv types, Env values)
     case Expression::Kind::StringTypeLiteral:
     case Expression::Kind::TypeTypeLiteral:
     case Expression::Kind::ContinuationTypeLiteral:
-      return TCExpression(e, global_arena->New<TypeType>(), types);
+      return TCExpression(e, global_arena->RawNew<TypeType>(), types);
   }
 }
 
@@ -520,8 +530,9 @@ auto TypeCheckPattern(const Pattern* p, TypeEnv types, Env values,
   }
   switch (p->Tag()) {
     case Pattern::Kind::AutoPattern: {
-      return {
-          .pattern = p, .type = global_arena->New<TypeType>(), .types = types};
+      return {.pattern = p,
+              .type = global_arena->RawNew<TypeType>(),
+              .types = types};
     }
     case Pattern::Kind::BindingPattern: {
       const auto& binding = cast<BindingPattern>(*p);
@@ -552,9 +563,9 @@ auto TypeCheckPattern(const Pattern* p, TypeEnv types, Env values,
           FATAL_COMPILATION_ERROR(binding.LineNumber())
               << "Unsupported type pattern";
       }
-      auto new_p = global_arena->New<BindingPattern>(
+      auto new_p = global_arena->RawNew<BindingPattern>(
           binding.LineNumber(), binding.Name(),
-          global_arena->New<ExpressionPattern>(
+          global_arena->RawNew<ExpressionPattern>(
               ReifyType(type, binding.LineNumber())));
       if (binding.Name().has_value()) {
         types.Set(*binding.Name(), type);
@@ -595,8 +606,8 @@ auto TypeCheckPattern(const Pattern* p, TypeEnv types, Env values,
         field_types.push_back({.name = field.name, .value = field_result.type});
       }
       auto new_tuple =
-          global_arena->New<TuplePattern>(tuple.LineNumber(), new_fields);
-      auto tuple_t = global_arena->New<TupleValue>(std::move(field_types));
+          global_arena->RawNew<TuplePattern>(tuple.LineNumber(), new_fields);
+      auto tuple_t = global_arena->RawNew<TupleValue>(std::move(field_types));
       return {.pattern = new_tuple, .type = tuple_t, .types = new_types};
     }
     case Pattern::Kind::AlternativePattern: {
@@ -620,7 +631,7 @@ auto TypeCheckPattern(const Pattern* p, TypeEnv types, Env values,
       }
       TCPattern arg_results = TypeCheckPattern(alternative.Arguments(), types,
                                                values, parameter_types);
-      return {.pattern = global_arena->New<AlternativePattern>(
+      return {.pattern = global_arena->RawNew<AlternativePattern>(
                   alternative.LineNumber(),
                   ReifyType(choice_type, alternative.LineNumber()),
                   alternative.AlternativeName(),
@@ -631,7 +642,7 @@ auto TypeCheckPattern(const Pattern* p, TypeEnv types, Env values,
     case Pattern::Kind::ExpressionPattern: {
       TCExpression result =
           TypeCheckExp(cast<ExpressionPattern>(p)->Expression(), types, values);
-      return {.pattern = global_arena->New<ExpressionPattern>(result.exp),
+      return {.pattern = global_arena->RawNew<ExpressionPattern>(result.exp),
               .type = result.type,
               .types = result.types};
     }
@@ -666,27 +677,26 @@ auto TypeCheckStmt(const Statement* s, TypeEnv types, Env values,
       const auto& match = cast<Match>(*s);
       auto res = TypeCheckExp(match.Exp(), types, values);
       auto res_type = res.type;
-      auto new_clauses =
-          global_arena
-              ->New<std::list<std::pair<const Pattern*, const Statement*>>>();
+      auto new_clauses = global_arena->RawNew<
+          std::list<std::pair<const Pattern*, const Statement*>>>();
       for (auto& clause : *match.Clauses()) {
         new_clauses->push_back(TypecheckCase(res_type, clause.first,
                                              clause.second, types, values,
                                              ret_type, is_omitted_ret_type));
       }
       const Statement* new_s =
-          global_arena->New<Match>(s->LineNumber(), res.exp, new_clauses);
+          global_arena->RawNew<Match>(s->LineNumber(), res.exp, new_clauses);
       return TCStatement(new_s, types);
     }
     case Statement::Kind::While: {
       const auto& while_stmt = cast<While>(*s);
       auto cnd_res = TypeCheckExp(while_stmt.Cond(), types, values);
       ExpectType(s->LineNumber(), "condition of `while`",
-                 global_arena->New<BoolType>(), cnd_res.type);
+                 global_arena->RawNew<BoolType>(), cnd_res.type);
       auto body_res = TypeCheckStmt(while_stmt.Body(), types, values, ret_type,
                                     is_omitted_ret_type);
-      auto new_s =
-          global_arena->New<While>(s->LineNumber(), cnd_res.exp, body_res.stmt);
+      auto new_s = global_arena->RawNew<While>(s->LineNumber(), cnd_res.exp,
+                                               body_res.stmt);
       return TCStatement(new_s, types);
     }
     case Statement::Kind::Break:
@@ -696,14 +706,14 @@ auto TypeCheckStmt(const Statement* s, TypeEnv types, Env values,
       auto stmt_res = TypeCheckStmt(cast<Block>(*s).Stmt(), types, values,
                                     ret_type, is_omitted_ret_type);
       return TCStatement(
-          global_arena->New<Block>(s->LineNumber(), stmt_res.stmt), types);
+          global_arena->RawNew<Block>(s->LineNumber(), stmt_res.stmt), types);
     }
     case Statement::Kind::VariableDefinition: {
       const auto& var = cast<VariableDefinition>(*s);
       auto res = TypeCheckExp(var.Init(), types, values);
       const Value* rhs_ty = res.type;
       auto lhs_res = TypeCheckPattern(var.Pat(), types, values, rhs_ty);
-      const Statement* new_s = global_arena->New<VariableDefinition>(
+      const Statement* new_s = global_arena->RawNew<VariableDefinition>(
           s->LineNumber(), var.Pat(), res.exp);
       return TCStatement(new_s, lhs_res.types);
     }
@@ -715,7 +725,7 @@ auto TypeCheckStmt(const Statement* s, TypeEnv types, Env values,
       auto next_res = TypeCheckStmt(seq.Next(), types2, values, ret_type,
                                     is_omitted_ret_type);
       auto types3 = next_res.types;
-      return TCStatement(global_arena->New<Sequence>(
+      return TCStatement(global_arena->RawNew<Sequence>(
                              s->LineNumber(), stmt_res.stmt, next_res.stmt),
                          types3);
     }
@@ -726,28 +736,28 @@ auto TypeCheckStmt(const Statement* s, TypeEnv types, Env values,
       auto lhs_res = TypeCheckExp(assign.Lhs(), types, values);
       auto lhs_t = lhs_res.type;
       ExpectType(s->LineNumber(), "assign", lhs_t, rhs_t);
-      auto new_s =
-          global_arena->New<Assign>(s->LineNumber(), lhs_res.exp, rhs_res.exp);
+      auto new_s = global_arena->RawNew<Assign>(s->LineNumber(), lhs_res.exp,
+                                                rhs_res.exp);
       return TCStatement(new_s, lhs_res.types);
     }
     case Statement::Kind::ExpressionStatement: {
       auto res =
           TypeCheckExp(cast<ExpressionStatement>(*s).Exp(), types, values);
       auto new_s =
-          global_arena->New<ExpressionStatement>(s->LineNumber(), res.exp);
+          global_arena->RawNew<ExpressionStatement>(s->LineNumber(), res.exp);
       return TCStatement(new_s, types);
     }
     case Statement::Kind::If: {
       const auto& if_stmt = cast<If>(*s);
       auto cnd_res = TypeCheckExp(if_stmt.Cond(), types, values);
       ExpectType(s->LineNumber(), "condition of `if`",
-                 global_arena->New<BoolType>(), cnd_res.type);
+                 global_arena->RawNew<BoolType>(), cnd_res.type);
       auto then_res = TypeCheckStmt(if_stmt.ThenStmt(), types, values, ret_type,
                                     is_omitted_ret_type);
       auto else_res = TypeCheckStmt(if_stmt.ElseStmt(), types, values, ret_type,
                                     is_omitted_ret_type);
-      auto new_s = global_arena->New<If>(s->LineNumber(), cnd_res.exp,
-                                         then_res.stmt, else_res.stmt);
+      auto new_s = global_arena->RawNew<If>(s->LineNumber(), cnd_res.exp,
+                                            then_res.stmt, else_res.stmt);
       return TCStatement(new_s, types);
     }
     case Statement::Kind::Return: {
@@ -766,27 +776,28 @@ auto TypeCheckStmt(const Statement* s, TypeEnv types, Env values,
             << *s << " should" << (is_omitted_ret_type ? " not" : "")
             << " provide a return value, to match the function's signature.";
       }
-      return TCStatement(global_arena->New<Return>(s->LineNumber(), res.exp,
-                                                   ret.IsOmittedExp()),
+      return TCStatement(global_arena->RawNew<Return>(s->LineNumber(), res.exp,
+                                                      ret.IsOmittedExp()),
                          types);
     }
     case Statement::Kind::Continuation: {
       const auto& cont = cast<Continuation>(*s);
       TCStatement body_result = TypeCheckStmt(cont.Body(), types, values,
                                               ret_type, is_omitted_ret_type);
-      const Statement* new_continuation = global_arena->New<Continuation>(
+      const Statement* new_continuation = global_arena->RawNew<Continuation>(
           s->LineNumber(), cont.ContinuationVariable(), body_result.stmt);
       types.Set(cont.ContinuationVariable(),
-                global_arena->New<ContinuationType>());
+                global_arena->RawNew<ContinuationType>());
       return TCStatement(new_continuation, types);
     }
     case Statement::Kind::Run: {
       TCExpression argument_result =
           TypeCheckExp(cast<Run>(*s).Argument(), types, values);
       ExpectType(s->LineNumber(), "argument of `run`",
-                 global_arena->New<ContinuationType>(), argument_result.type);
+                 global_arena->RawNew<ContinuationType>(),
+                 argument_result.type);
       const Statement* new_run =
-          global_arena->New<Run>(s->LineNumber(), argument_result.exp);
+          global_arena->RawNew<Run>(s->LineNumber(), argument_result.exp);
       return TCStatement(new_run, types);
     }
     case Statement::Kind::Await: {
@@ -800,8 +811,8 @@ static auto CheckOrEnsureReturn(const Statement* stmt, bool omitted_ret_type,
                                 int line_num) -> const Statement* {
   if (!stmt) {
     if (omitted_ret_type) {
-      return global_arena->New<Return>(line_num, nullptr,
-                                       /*is_omitted_exp=*/true);
+      return global_arena->RawNew<Return>(line_num, nullptr,
+                                          /*is_omitted_exp=*/true);
     } else {
       FATAL_COMPILATION_ERROR(line_num)
           << "control-flow reaches end of function that provides a `->` return "
@@ -811,25 +822,24 @@ static auto CheckOrEnsureReturn(const Statement* stmt, bool omitted_ret_type,
   switch (stmt->Tag()) {
     case Statement::Kind::Match: {
       const auto& match = cast<Match>(*stmt);
-      auto new_clauses =
-          global_arena
-              ->New<std::list<std::pair<const Pattern*, const Statement*>>>();
+      auto new_clauses = global_arena->RawNew<
+          std::list<std::pair<const Pattern*, const Statement*>>>();
       for (const auto& clause : *match.Clauses()) {
         auto s = CheckOrEnsureReturn(clause.second, omitted_ret_type,
                                      stmt->LineNumber());
         new_clauses->push_back(std::make_pair(clause.first, s));
       }
-      return global_arena->New<Match>(stmt->LineNumber(), match.Exp(),
-                                      new_clauses);
+      return global_arena->RawNew<Match>(stmt->LineNumber(), match.Exp(),
+                                         new_clauses);
     }
     case Statement::Kind::Block:
-      return global_arena->New<Block>(
+      return global_arena->RawNew<Block>(
           stmt->LineNumber(),
           CheckOrEnsureReturn(cast<Block>(*stmt).Stmt(), omitted_ret_type,
                               stmt->LineNumber()));
     case Statement::Kind::If: {
       const auto& if_stmt = cast<If>(*stmt);
-      return global_arena->New<If>(
+      return global_arena->RawNew<If>(
           stmt->LineNumber(), if_stmt.Cond(),
           CheckOrEnsureReturn(if_stmt.ThenStmt(), omitted_ret_type,
                               stmt->LineNumber()),
@@ -841,7 +851,7 @@ static auto CheckOrEnsureReturn(const Statement* stmt, bool omitted_ret_type,
     case Statement::Kind::Sequence: {
       const auto& seq = cast<Sequence>(*stmt);
       if (seq.Next()) {
-        return global_arena->New<Sequence>(
+        return global_arena->RawNew<Sequence>(
             stmt->LineNumber(), seq.Stmt(),
             CheckOrEnsureReturn(seq.Next(), omitted_ret_type,
                                 stmt->LineNumber()));
@@ -861,10 +871,10 @@ static auto CheckOrEnsureReturn(const Statement* stmt, bool omitted_ret_type,
     case Statement::Kind::Continue:
     case Statement::Kind::VariableDefinition:
       if (omitted_ret_type) {
-        return global_arena->New<Sequence>(
+        return global_arena->RawNew<Sequence>(
             stmt->LineNumber(), stmt,
-            global_arena->New<Return>(line_num, nullptr,
-                                      /*is_omitted_exp=*/true));
+            global_arena->RawNew<Return>(line_num, nullptr,
+                                         /*is_omitted_exp=*/true));
       } else {
         FATAL_COMPILATION_ERROR(stmt->LineNumber())
             << "control-flow reaches end of function that provides a `->` "
@@ -883,7 +893,7 @@ static auto TypeCheckFunDef(const FunctionDefinition* f, TypeEnv types,
   for (const auto& deduced : f->deduced_parameters) {
     // auto t = InterpExp(values, deduced.type);
     Address a = state->heap.AllocateValue(
-        global_arena->New<VariableType>(deduced.name));
+        global_arena->RawNew<VariableType>(deduced.name));
     values.Set(deduced.name, a);
   }
   // Type check the parameter pattern
@@ -892,16 +902,17 @@ static auto TypeCheckFunDef(const FunctionDefinition* f, TypeEnv types,
   auto return_type = InterpPattern(values, f->return_type);
   if (f->name == "main") {
     ExpectType(f->line_num, "return type of `main`",
-               global_arena->New<IntType>(), return_type);
+               global_arena->RawNew<IntType>(), return_type);
     // TODO: Check that main doesn't have any parameters.
   }
   auto res = TypeCheckStmt(f->body, param_res.types, values, return_type,
                            f->is_omitted_return_type);
   auto body =
       CheckOrEnsureReturn(res.stmt, f->is_omitted_return_type, f->line_num);
-  return global_arena->New<FunctionDefinition>(
+  return global_arena->RawNew<FunctionDefinition>(
       f->line_num, f->name, f->deduced_parameters, f->param_pattern,
-      global_arena->New<ExpressionPattern>(ReifyType(return_type, f->line_num)),
+      global_arena->RawNew<ExpressionPattern>(
+          ReifyType(return_type, f->line_num)),
       /*is_omitted_return_type=*/false, body);
 }
 
@@ -911,7 +922,7 @@ static auto TypeOfFunDef(TypeEnv types, Env values,
   for (const auto& deduced : fun_def->deduced_parameters) {
     // auto t = InterpExp(values, deduced.type);
     Address a = state->heap.AllocateValue(
-        global_arena->New<VariableType>(deduced.name));
+        global_arena->RawNew<VariableType>(deduced.name));
     values.Set(deduced.name, a);
   }
   // Type check the parameter pattern
@@ -923,8 +934,8 @@ static auto TypeOfFunDef(TypeEnv types, Env values,
     auto f = TypeCheckFunDef(fun_def, types, values);
     ret = InterpPattern(values, f->return_type);
   }
-  return global_arena->New<FunctionType>(fun_def->deduced_parameters,
-                                         param_res.type, ret);
+  return global_arena->RawNew<FunctionType>(fun_def->deduced_parameters,
+                                            param_res.type, ret);
 }
 
 static auto TypeOfStructDef(const StructDefinition* sd, TypeEnv /*types*/,
@@ -951,8 +962,8 @@ static auto TypeOfStructDef(const StructDefinition* sd, TypeEnv /*types*/,
       }
     }
   }
-  return global_arena->New<StructType>(sd->name, std::move(fields),
-                                       std::move(methods));
+  return global_arena->RawNew<StructType>(sd->name, std::move(fields),
+                                          std::move(methods));
 }
 
 static auto GetName(const Declaration& d) -> const std::string& {
@@ -978,7 +989,7 @@ auto MakeTypeChecked(const Declaration& d, const TypeEnv& types,
                      const Env& values) -> const Declaration* {
   switch (d.Tag()) {
     case Declaration::Kind::FunctionDeclaration:
-      return global_arena->New<FunctionDeclaration>(TypeCheckFunDef(
+      return global_arena->RawNew<FunctionDeclaration>(TypeCheckFunDef(
           &cast<FunctionDeclaration>(d).Definition(), types, values));
 
     case Declaration::Kind::StructDeclaration: {
@@ -993,7 +1004,7 @@ auto MakeTypeChecked(const Declaration& d, const TypeEnv& types,
             break;
         }
       }
-      return global_arena->New<StructDeclaration>(
+      return global_arena->RawNew<StructDeclaration>(
           struct_def.line_num, struct_def.name, std::move(fields));
     }
 
@@ -1045,9 +1056,9 @@ static void TopLevel(const Declaration& d, TypeCheckContext* tops) {
            cast<StructType>(*st).Fields()) {
         field_types.push_back({.name = field_name, .value = field_value});
       }
-      auto fun_ty = global_arena->New<FunctionType>(
+      auto fun_ty = global_arena->RawNew<FunctionType>(
           std::vector<GenericBinding>(),
-          global_arena->New<TupleValue>(std::move(field_types)), st);
+          global_arena->RawNew<TupleValue>(std::move(field_types)), st);
       tops->types.Set(struct_def.name, fun_ty);
       break;
     }
@@ -1059,7 +1070,8 @@ static void TopLevel(const Declaration& d, TypeCheckContext* tops) {
         auto t = InterpExp(tops->values, signature);
         alts.push_back(std::make_pair(name, t));
       }
-      auto ct = global_arena->New<ChoiceType>(choice.Name(), std::move(alts));
+      auto ct =
+          global_arena->RawNew<ChoiceType>(choice.Name(), std::move(alts));
       Address a = state->heap.AllocateValue(ct);
       tops->values.Set(choice.Name(), a);  // Is this obsolete?
       tops->types.Set(choice.Name(), ct);
diff --git a/executable_semantics/interpreter/value.cpp b/executable_semantics/interpreter/value.cpp
index caab69b3e6e8..d08cbc304dda 100644
--- a/executable_semantics/interpreter/value.cpp
+++ b/executable_semantics/interpreter/value.cpp
@@ -78,7 +78,8 @@ auto GetMember(const Value* v, const std::string& f, int line_num)
         FATAL_RUNTIME_ERROR(line_num)
             << "alternative " << f << " not in " << *v;
       }
-      return global_arena->New<AlternativeConstructorValue>(f, choice.Name());
+      return global_arena->RawNew<AlternativeConstructorValue>(f,
+                                                               choice.Name());
     }
     default:
       FATAL() << "field access not allowed for value " << *v;
@@ -122,7 +123,7 @@ auto SetFieldImpl(const Value* value,
       }
       it->value = SetFieldImpl(it->value, path_begin + 1, path_end, field_value,
                                line_num);
-      return global_arena->New<TupleValue>(elements);
+      return global_arena->RawNew<TupleValue>(elements);
     }
     default:
       FATAL() << "field access not allowed for value " << *value;
@@ -255,56 +256,56 @@ auto CopyVal(const Value* val, int line_num) -> const Value* {
         elements.push_back(
             {.name = element.name, .value = CopyVal(element.value, line_num)});
       }
-      return global_arena->New<TupleValue>(std::move(elements));
+      return global_arena->RawNew<TupleValue>(std::move(elements));
     }
     case Value::Kind::AlternativeValue: {
       const auto& alt = cast<AlternativeValue>(*val);
       const Value* arg = CopyVal(alt.Argument(), line_num);
-      return global_arena->New<AlternativeValue>(alt.AltName(),
-                                                 alt.ChoiceName(), arg);
+      return global_arena->RawNew<AlternativeValue>(alt.AltName(),
+                                                    alt.ChoiceName(), arg);
     }
     case Value::Kind::StructValue: {
       const auto& s = cast<StructValue>(*val);
       const Value* inits = CopyVal(s.Inits(), line_num);
-      return global_arena->New<StructValue>(s.Type(), inits);
+      return global_arena->RawNew<StructValue>(s.Type(), inits);
     }
     case Value::Kind::IntValue:
-      return global_arena->New<IntValue>(cast<IntValue>(*val).Val());
+      return global_arena->RawNew<IntValue>(cast<IntValue>(*val).Val());
     case Value::Kind::BoolValue:
-      return global_arena->New<BoolValue>(cast<BoolValue>(*val).Val());
+      return global_arena->RawNew<BoolValue>(cast<BoolValue>(*val).Val());
     case Value::Kind::FunctionValue: {
       const auto& fn_value = cast<FunctionValue>(*val);
-      return global_arena->New<FunctionValue>(fn_value.Name(), fn_value.Param(),
-                                              fn_value.Body());
+      return global_arena->RawNew<FunctionValue>(
+          fn_value.Name(), fn_value.Param(), fn_value.Body());
     }
     case Value::Kind::PointerValue:
-      return global_arena->New<PointerValue>(cast<PointerValue>(*val).Val());
+      return global_arena->RawNew<PointerValue>(cast<PointerValue>(*val).Val());
     case Value::Kind::ContinuationValue:
       // Copying a continuation is "shallow".
       return val;
     case Value::Kind::FunctionType: {
       const auto& fn_type = cast<FunctionType>(*val);
-      return global_arena->New<FunctionType>(fn_type.Deduced(),
-                                             CopyVal(fn_type.Param(), line_num),
-                                             CopyVal(fn_type.Ret(), line_num));
+      return global_arena->RawNew<FunctionType>(
+          fn_type.Deduced(), CopyVal(fn_type.Param(), line_num),
+          CopyVal(fn_type.Ret(), line_num));
     }
     case Value::Kind::PointerType:
-      return global_arena->New<PointerType>(
+      return global_arena->RawNew<PointerType>(
           CopyVal(cast<PointerType>(*val).Type(), line_num));
     case Value::Kind::IntType:
-      return global_arena->New<IntType>();
+      return global_arena->RawNew<IntType>();
     case Value::Kind::BoolType:
-      return global_arena->New<BoolType>();
+      return global_arena->RawNew<BoolType>();
     case Value::Kind::TypeType:
-      return global_arena->New<TypeType>();
+      return global_arena->RawNew<TypeType>();
     case Value::Kind::AutoType:
-      return global_arena->New<AutoType>();
+      return global_arena->RawNew<AutoType>();
     case Value::Kind::ContinuationType:
-      return global_arena->New<ContinuationType>();
+      return global_arena->RawNew<ContinuationType>();
     case Value::Kind::StringType:
-      return global_arena->New<StringType>();
+      return global_arena->RawNew<StringType>();
     case Value::Kind::StringValue:
-      return global_arena->New<StringValue>(cast<StringValue>(*val).Val());
+      return global_arena->RawNew<StringValue>(cast<StringValue>(*val).Val());
     case Value::Kind::VariableType:
     case Value::Kind::StructType:
     case Value::Kind::ChoiceType:
diff --git a/executable_semantics/syntax/parser.ypp b/executable_semantics/syntax/parser.ypp
index fab87935a4cf..1e96da9a5aad 100644
--- a/executable_semantics/syntax/parser.ypp
+++ b/executable_semantics/syntax/parser.ypp
@@ -213,75 +213,75 @@ input: declaration_list
 ;
 expression:
   identifier
-    { $$ = global_arena->New<IdentifierExpression>(yylineno, $1); }
+    { $$ = global_arena->RawNew<IdentifierExpression>(yylineno, $1); }
 | expression designator
-    { $$ = global_arena->New<FieldAccessExpression>(yylineno, $1, $2); }
+    { $$ = global_arena->RawNew<FieldAccessExpression>(yylineno, $1, $2); }
 | expression "[" expression "]"
-    { $$ = global_arena->New<IndexExpression>(yylineno, $1, $3); }
+    { $$ = global_arena->RawNew<IndexExpression>(yylineno, $1, $3); }
 | integer_literal
-    { $$ = global_arena->New<IntLiteral>(yylineno, $1); }
+    { $$ = global_arena->RawNew<IntLiteral>(yylineno, $1); }
 | string_literal
-    { $$ = global_arena->New<StringLiteral>(yylineno, $1); }
+    { $$ = global_arena->RawNew<StringLiteral>(yylineno, $1); }
 | TRUE
-    { $$ = global_arena->New<BoolLiteral>(yylineno, true); }
+    { $$ = global_arena->RawNew<BoolLiteral>(yylineno, true); }
 | FALSE
-    { $$ = global_arena->New<BoolLiteral>(yylineno, false); }
+    { $$ = global_arena->RawNew<BoolLiteral>(yylineno, false); }
 | sized_type_literal
     {
       int val;
       CHECK(llvm::to_integer(llvm::StringRef($1).substr(1), val));
       CHECK($1[0] == 'i' && val == 32)  << "Only i32 is supported for now: " << $1;
-      $$ = global_arena->New<IntTypeLiteral>(yylineno);
+      $$ = global_arena->RawNew<IntTypeLiteral>(yylineno);
     }
 | STRING
-    { $$ = global_arena->New<StringTypeLiteral>(yylineno); }
+    { $$ = global_arena->RawNew<StringTypeLiteral>(yylineno); }
 | BOOL
-    { $$ = global_arena->New<BoolTypeLiteral>(yylineno); }
+    { $$ = global_arena->RawNew<BoolTypeLiteral>(yylineno); }
 | TYPE
-    { $$ = global_arena->New<TypeTypeLiteral>(yylineno); }
+    { $$ = global_arena->RawNew<TypeTypeLiteral>(yylineno); }
 | CONTINUATION_TYPE
-    { $$ = global_arena->New<ContinuationTypeLiteral>(yylineno); }
+    { $$ = global_arena->RawNew<ContinuationTypeLiteral>(yylineno); }
 | paren_expression { $$ = $1; }
 | expression EQUAL_EQUAL expression
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Eq, std::vector<const Expression*>({$1, $3})); }
 | expression "+" expression
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Add, std::vector<const Expression*>({$1, $3})); }
 | expression "-" expression
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Sub, std::vector<const Expression*>({$1, $3})); }
 | expression BINARY_STAR expression
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Mul, std::vector<const Expression*>({$1, $3})); }
 | expression AND expression
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::And, std::vector<const Expression*>({$1, $3})); }
 | expression OR expression
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Or, std::vector<const Expression*>({$1, $3})); }
 | NOT expression
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Not, std::vector<const Expression*>({$2})); }
 | "-" expression %prec UNARY_MINUS
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Neg, std::vector<const Expression*>({$2})); }
 | PREFIX_STAR expression
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Deref, std::vector<const Expression*>({$2})); }
 | UNARY_STAR expression %prec PREFIX_STAR
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Deref, std::vector<const Expression*>({$2})); }
 | expression tuple
-    { $$ = global_arena->New<CallExpression>(yylineno, $1, $2); }
+    { $$ = global_arena->RawNew<CallExpression>(yylineno, $1, $2); }
 | expression POSTFIX_STAR
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Ptr, std::vector<const Expression*>({$1})); }
 | expression UNARY_STAR
-    { $$ = global_arena->New<PrimitiveOperatorExpression>(
+    { $$ = global_arena->RawNew<PrimitiveOperatorExpression>(
         yylineno, Operator::Ptr, std::vector<const Expression*>({$1})); }
 | FNTY tuple return_type
-    { $$ = global_arena->New<FunctionTypeLiteral>(
+    { $$ = global_arena->RawNew<FunctionTypeLiteral>(
         yylineno, $2, $3.first, $3.second); }
 ;
 designator: "." identifier { $$ = $2; }
@@ -329,17 +329,17 @@ pattern:
   non_expression_pattern
     { $$ = $1; }
 | expression
-    { $$ = global_arena->New<ExpressionPattern>($1); }
+    { $$ = global_arena->RawNew<ExpressionPattern>($1); }
 ;
 non_expression_pattern:
   AUTO
-    { $$ = global_arena->New<AutoPattern>(yylineno); }
+    { $$ = global_arena->RawNew<AutoPattern>(yylineno); }
 | binding_lhs ":" pattern
-    { $$ = global_arena->New<BindingPattern>(yylineno, $1, $3); }
+    { $$ = global_arena->RawNew<BindingPattern>(yylineno, $1, $3); }
 | paren_pattern
     { $$ = $1; }
 | expression tuple_pattern
-    { $$ = global_arena->New<AlternativePattern>(yylineno, $1, $2); }
+    { $$ = global_arena->RawNew<AlternativePattern>(yylineno, $1, $2); }
 ;
 binding_lhs:
   identifier { $$ = $1; }
@@ -373,7 +373,7 @@ paren_pattern_contents:
 | paren_pattern_contents "," paren_expression_element
     {
       $$ = $1;
-      $$.elements.push_back({.name = $3.name, .term = global_arena->New<ExpressionPattern>($3.term)});
+      $$.elements.push_back({.name = $3.name, .term = global_arena->RawNew<ExpressionPattern>($3.term)});
     }
 | paren_pattern_contents "," paren_pattern_element
     {
@@ -395,24 +395,24 @@ tuple_pattern: paren_pattern_base
 // rules out the possibility of an `expression` at this point.
 maybe_empty_tuple_pattern:
   "(" ")"
-    { $$ = global_arena->New<TuplePattern>(yylineno, std::vector<TuplePattern::Field>()); }
+    { $$ = global_arena->RawNew<TuplePattern>(yylineno, std::vector<TuplePattern::Field>()); }
 | tuple_pattern
     { $$ = $1; }
 ;
 clause:
   CASE pattern DBLARROW statement
-    { $$ = global_arena->New<std::pair<const Pattern*, const Statement*>>($2, $4); }
+    { $$ = global_arena->RawNew<std::pair<const Pattern*, const Statement*>>($2, $4); }
 | DEFAULT DBLARROW statement
     {
-      auto vp = global_arena->New<BindingPattern>(
-          yylineno, std::nullopt, global_arena->New<AutoPattern>(yylineno));
-      $$ = global_arena->New<std::pair<const Pattern*, const Statement*>>(vp, $3);
+      auto vp = global_arena->RawNew<BindingPattern>(
+          yylineno, std::nullopt, global_arena->RawNew<AutoPattern>(yylineno));
+      $$ = global_arena->RawNew<std::pair<const Pattern*, const Statement*>>(vp, $3);
     }
 ;
 clause_list:
   // Empty
     {
-      $$ = global_arena->New<std::list<
+      $$ = global_arena->RawNew<std::list<
           std::pair<const Pattern*, const Statement*>>>();
     }
 | clause clause_list
@@ -420,35 +420,35 @@ clause_list:
 ;
 statement:
   expression "=" expression ";"
-    { $$ = global_arena->New<Assign>(yylineno, $1, $3); }
+    { $$ = global_arena->RawNew<Assign>(yylineno, $1, $3); }
 | VAR pattern "=" expression ";"
-    { $$ = global_arena->New<VariableDefinition>(yylineno, $2, $4); }
+    { $$ = global_arena->RawNew<VariableDefinition>(yylineno, $2, $4); }
 | expression ";"
-    { $$ = global_arena->New<ExpressionStatement>(yylineno, $1); }
+    { $$ = global_arena->RawNew<ExpressionStatement>(yylineno, $1); }
 | if_statement
     { $$ = $1; }
 | WHILE "(" expression ")" block
-    { $$ = global_arena->New<While>(yylineno, $3, $5); }
+    { $$ = global_arena->RawNew<While>(yylineno, $3, $5); }
 | BREAK ";"
-    { $$ = global_arena->New<Break>(yylineno); }
+    { $$ = global_arena->RawNew<Break>(yylineno); }
 | CONTINUE ";"
-    { $$ = global_arena->New<Continue>(yylineno); }
+    { $$ = global_arena->RawNew<Continue>(yylineno); }
 | RETURN return_expression ";"
-    { $$ = global_arena->New<Return>(yylineno, $2.first, $2.second); }
+    { $$ = global_arena->RawNew<Return>(yylineno, $2.first, $2.second); }
 | block
     { $$ = $1; }
 | MATCH "(" expression ")" "{" clause_list "}"
-    { $$ = global_arena->New<Match>(yylineno, $3, $6); }
+    { $$ = global_arena->RawNew<Match>(yylineno, $3, $6); }
 | CONTINUATION identifier statement
-    { $$ = global_arena->New<Continuation>(yylineno, $2, $3); }
+    { $$ = global_arena->RawNew<Continuation>(yylineno, $2, $3); }
 | RUN expression ";"
-    { $$ = global_arena->New<Run>(yylineno, $2); }
+    { $$ = global_arena->RawNew<Run>(yylineno, $2); }
 | AWAIT ";"
-    { $$ = global_arena->New<Await>(yylineno); }
+    { $$ = global_arena->RawNew<Await>(yylineno); }
 ;
 if_statement:
   IF "(" expression ")" block optional_else
-    { $$ = global_arena->New<If>(yylineno, $3, $5, $6); }
+    { $$ = global_arena->RawNew<If>(yylineno, $3, $5, $6); }
 ;
 optional_else:
   // Empty
@@ -460,7 +460,7 @@ optional_else:
 ;
 return_expression:
   // Empty
-    { $$ = {global_arena->New<TupleLiteral>(yylineno), true}; }
+    { $$ = {global_arena->RawNew<TupleLiteral>(yylineno), true}; }
 | expression
     { $$ = {$1, false}; }
 ;
@@ -468,15 +468,15 @@ statement_list:
   // Empty
     { $$ = 0; }
 | statement statement_list
-    { $$ = global_arena->New<Sequence>(yylineno, $1, $2); }
+    { $$ = global_arena->RawNew<Sequence>(yylineno, $1, $2); }
 ;
 block:
   "{" statement_list "}"
-    { $$ = global_arena->New<Block>(yylineno, $2); }
+    { $$ = global_arena->RawNew<Block>(yylineno, $2); }
 ;
 return_type:
   // Empty
-    { $$ = {global_arena->New<TupleLiteral>(yylineno), true}; }
+    { $$ = {global_arena->RawNew<TupleLiteral>(yylineno), true}; }
 | ARROW expression %prec FNARROW
     { $$ = {$2, false}; }
 ;
@@ -509,34 +509,34 @@ deduced_params:
 function_definition:
   FN identifier deduced_params maybe_empty_tuple_pattern return_type block
     {
-      $$ = global_arena->New<FunctionDefinition>(
+      $$ = global_arena->RawNew<FunctionDefinition>(
           yylineno, $2, $3, $4,
-          global_arena->New<ExpressionPattern>($5.first),
+          global_arena->RawNew<ExpressionPattern>($5.first),
           $5.second, $6);
     }
 | FN identifier deduced_params maybe_empty_tuple_pattern DBLARROW expression ";"
     {
       // The return type is not considered "omitted" because it's automatic from
       // the expression.
-      $$ = global_arena->New<FunctionDefinition>(
+      $$ = global_arena->RawNew<FunctionDefinition>(
           yylineno, $2, $3, $4,
-          global_arena->New<AutoPattern>(yylineno), true,
-          global_arena->New<Return>(yylineno, $6, true));
+          global_arena->RawNew<AutoPattern>(yylineno), true,
+          global_arena->RawNew<Return>(yylineno, $6, true));
     }
 ;
 function_declaration:
   FN identifier deduced_params maybe_empty_tuple_pattern return_type ";"
     {
-      $$ = global_arena->New<FunctionDefinition>(
+      $$ = global_arena->RawNew<FunctionDefinition>(
           yylineno, $2, $3, $4,
-          global_arena->New<ExpressionPattern>($5.first),
+          global_arena->RawNew<ExpressionPattern>($5.first),
           $5.second, nullptr); }
 ;
 variable_declaration: identifier ":" pattern
-    { $$ = global_arena->New<BindingPattern>(yylineno, $1, $3); }
+    { $$ = global_arena->RawNew<BindingPattern>(yylineno, $1, $3); }
 ;
 member: VAR variable_declaration ";"
-    { $$ = global_arena->New<FieldMember>(yylineno, $2); }
+    { $$ = global_arena->RawNew<FieldMember>(yylineno, $2); }
 ;
 member_list:
   // Empty
@@ -550,7 +550,7 @@ alternative:
 | identifier
     {
       $$ = std::pair<std::string, const Expression*>(
-          $1, global_arena->New<TupleLiteral>(yylineno));
+          $1, global_arena->RawNew<TupleLiteral>(yylineno));
     }
 ;
 alternative_list:
@@ -566,20 +566,20 @@ alternative_list:
 ;
 declaration:
   function_definition
-    { $$ = global_arena->New<FunctionDeclaration>($1); }
+    { $$ = global_arena->RawNew<FunctionDeclaration>($1); }
 | function_declaration
-    { $$ = global_arena->New<FunctionDeclaration>($1); }
+    { $$ = global_arena->RawNew<FunctionDeclaration>($1); }
 | STRUCT identifier "{" member_list "}"
     {
-      $$ = global_arena->New<StructDeclaration>(yylineno, $2, $4);
+      $$ = global_arena->RawNew<StructDeclaration>(yylineno, $2, $4);
     }
 | CHOICE identifier "{" alternative_list "}"
     {
-      $$ = global_arena->New<ChoiceDeclaration>(yylineno, $2, $4);
+      $$ = global_arena->RawNew<ChoiceDeclaration>(yylineno, $2, $4);
     }
 | VAR variable_declaration "=" expression ";"
     {
-      $$ = global_arena->New<VariableDeclaration>(yylineno, $2, $4);
+      $$ = global_arena->RawNew<VariableDeclaration>(yylineno, $2, $4);
     }
 ;
 declaration_list:
diff --git a/executable_semantics/syntax/syntax_helpers.cpp b/executable_semantics/syntax/syntax_helpers.cpp
index 47ccfce1d51f..260f41b4b202 100644
--- a/executable_semantics/syntax/syntax_helpers.cpp
+++ b/executable_semantics/syntax/syntax_helpers.cpp
@@ -17,21 +17,21 @@ namespace Carbon {
 // standardized, but is made available for printing state in tests.
 static void AddIntrinsics(std::list<const Declaration*>* fs) {
   std::vector<TuplePattern::Field> print_fields = {TuplePattern::Field(
-      "0", global_arena->New<BindingPattern>(
+      "0", global_arena->RawNew<BindingPattern>(
                -1, "format_str",
-               global_arena->New<ExpressionPattern>(
-                   global_arena->New<StringTypeLiteral>(-1))))};
-  auto* print_return =
-      global_arena->New<Return>(-1,
-                                global_arena->New<IntrinsicExpression>(
-                                    IntrinsicExpression::IntrinsicKind::Print),
-                                false);
-  auto* print = global_arena->New<FunctionDeclaration>(
-      global_arena->New<FunctionDefinition>(
+               global_arena->RawNew<ExpressionPattern>(
+                   global_arena->RawNew<StringTypeLiteral>(-1))))};
+  auto* print_return = global_arena->RawNew<Return>(
+      -1,
+      global_arena->RawNew<IntrinsicExpression>(
+          IntrinsicExpression::IntrinsicKind::Print),
+      false);
+  auto* print = global_arena->RawNew<FunctionDeclaration>(
+      global_arena->RawNew<FunctionDefinition>(
           -1, "Print", std::vector<GenericBinding>(),
-          global_arena->New<TuplePattern>(-1, print_fields),
-          global_arena->New<ExpressionPattern>(
-              global_arena->New<TupleLiteral>(-1)),
+          global_arena->RawNew<TuplePattern>(-1, print_fields),
+          global_arena->RawNew<ExpressionPattern>(
+              global_arena->RawNew<TupleLiteral>(-1)),
           /*is_omitted_return_type=*/false, print_return));
   fs->insert(fs->begin(), print);
 }
@@ -45,7 +45,7 @@ void ExecProgram(std::list<const Declaration*> fs) {
     }
     llvm::outs() << "********** type checking **********\n";
   }
-  state = global_arena->New<State>();  // Compile-time state.
+  state = global_arena->RawNew<State>();  // Compile-time state.
   TypeCheckContext p = TopLevel(fs);
   TypeEnv top = p.types;
   Env ct_top = p.values;