diff --git a/toolchain/check/name_lookup.cpp b/toolchain/check/name_lookup.cpp
index 571a2c174568..036cd3cd49e6 100644
--- a/toolchain/check/name_lookup.cpp
+++ b/toolchain/check/name_lookup.cpp
@@ -21,6 +21,7 @@
 #include "toolchain/sem_ir/generic.h"
 #include "toolchain/sem_ir/ids.h"
 #include "toolchain/sem_ir/name_scope.h"
+#include "toolchain/sem_ir/typed_insts.h"
 
 namespace Carbon::Check {
 
@@ -323,15 +324,16 @@ auto AppendLookupScopesForConstant(Context& context, SemIR::LocId loc_id,
                                    llvm::SmallVector<LookupScope>* scopes)
     -> bool {
   auto lookup_inst_id = context.constant_values().GetInstId(lookup_const_id);
-  auto lookup = context.insts().Get(lookup_inst_id);
 
-  if (auto ns = lookup.TryAs<SemIR::Namespace>()) {
+  if (auto ns = context.insts().TryGetAs<SemIR::Namespace>(lookup_inst_id)) {
     scopes->push_back(LookupScope{.name_scope_id = ns->name_scope_id,
                                   .specific_id = SemIR::SpecificId::None,
                                   .self_const_id = SemIR::ConstantId::None});
     return true;
   }
-  if (auto class_ty = lookup.TryAs<SemIR::ClassType>()) {
+
+  if (auto class_ty =
+          context.insts().TryGetAs<SemIR::ClassType>(lookup_inst_id)) {
     if (!extended_scope) {
       // TODO: Allow name lookup into classes that are being defined even if
       // they are not complete.
@@ -351,8 +353,14 @@ auto AppendLookupScopesForConstant(Context& context, SemIR::LocId loc_id,
                                   .self_const_id = self_type_const_id});
     return true;
   }
-  // Extended scopes may point to a FacetType.
-  if (auto facet_type = lookup.TryAs<SemIR::FacetType>()) {
+
+  // Extended scopes may point to a FacetType. If it has constraints, collect
+  // the extended ones as scopes.
+  auto lookup_type_id =
+      context.types().TryGetTypeIdForTypeInstId(lookup_inst_id);
+  if (lookup_type_id.has_value() &&
+      context.types().IsConstrainedFacetType(lookup_type_id)) {
+    auto facet_type = context.types().GetAs<SemIR::FacetType>(lookup_type_id);
     if (!extended_scope) {
       // TODO: Allow name lookup into facet types that are being defined even if
       // they are not complete.
@@ -378,7 +386,7 @@ auto AppendLookupScopesForConstant(Context& context, SemIR::LocId loc_id,
     }
 
     auto declared_facet_type =
-        context.declared_facet_types().Get(facet_type->declared_facet_type_id);
+        context.declared_facet_types().Get(facet_type.declared_facet_type_id);
     // Name lookup into "extend" constraints but not "self impls" constraints.
     for (const auto& extend : declared_facet_type.extend_constraints) {
       auto& interface = context.interfaces().Get(extend.interface_id);
@@ -413,6 +421,7 @@ auto AppendLookupScopesForConstant(Context& context, SemIR::LocId loc_id,
     }
     return true;
   }
+
   if (lookup_const_id == SemIR::ErrorInst::ConstantId) {
     // Lookup into this scope should fail without producing an error.
     scopes->push_back(LookupScope{.name_scope_id = SemIR::NameScopeId::None,
@@ -420,6 +429,7 @@ auto AppendLookupScopesForConstant(Context& context, SemIR::LocId loc_id,
                                   .self_const_id = SemIR::ConstantId::None});
     return true;
   }
+
   // TODO: Per the design, if `base_id` is any kind of type, then lookup should
   // treat it as a name scope, even if it doesn't have members. For example,
   // `(i32*).X` should fail because there's no name `X` in `i32*`, not because
diff --git a/toolchain/check/testdata/facet/aggregate_through_access.carbon b/toolchain/check/testdata/facet/aggregate_through_access.carbon
index f9292742f8da..280e30e9c06b 100644
--- a/toolchain/check/testdata/facet/aggregate_through_access.carbon
+++ b/toolchain/check/testdata/facet/aggregate_through_access.carbon
@@ -32,7 +32,7 @@ interface Z {
   let X: type;
 }
 
-// CHECK:STDERR: fail_todo_struct_access_through_witness.carbon:[[@LINE+4]]:43: error: member name `t` not found [MemberNameNotFound]
+// CHECK:STDERR: fail_todo_struct_access_through_witness.carbon:[[@LINE+4]]:43: error: type `type` does not support qualified expressions [QualifiedExprUnsupported]
 // CHECK:STDERR: fn F(generic T: Z where .X = {.t: ()}) -> T.X.t {
 // CHECK:STDERR:                                           ^~~~~
 // CHECK:STDERR:
diff --git a/toolchain/check/testdata/facet/runtime_value.carbon b/toolchain/check/testdata/facet/runtime_value.carbon
index d56fa28a0ea0..54bfb7bfb7b7 100644
--- a/toolchain/check/testdata/facet/runtime_value.carbon
+++ b/toolchain/check/testdata/facet/runtime_value.carbon
@@ -148,7 +148,7 @@ fn F(T: Z) {
 library "[[@TEST_NAME]]";
 
 fn F(T: type) {
-  // CHECK:STDERR: fail_member_access_runtime_type.carbon:[[@LINE+4]]:3: error: member name `G` not found [MemberNameNotFound]
+  // CHECK:STDERR: fail_member_access_runtime_type.carbon:[[@LINE+4]]:3: error: type `type` does not support qualified expressions [QualifiedExprUnsupported]
   // CHECK:STDERR:   T.G();
   // CHECK:STDERR:   ^~~
   // CHECK:STDERR:
diff --git a/toolchain/check/testdata/interface/fail_lookup_in_type_type.carbon b/toolchain/check/testdata/interface/fail_lookup_in_type_type.carbon
index 378e7e6ba47b..34a2cbbc6029 100644
--- a/toolchain/check/testdata/interface/fail_lookup_in_type_type.carbon
+++ b/toolchain/check/testdata/interface/fail_lookup_in_type_type.carbon
@@ -16,7 +16,7 @@
 
 library "[[@TEST_NAME]]";
 
-// CHECK:STDERR: fail_lookup_in_type.carbon:[[@LINE+4]]:8: error: member name `not_found` not found [MemberNameNotFound]
+// CHECK:STDERR: fail_lookup_in_type.carbon:[[@LINE+4]]:8: error: type `type` does not support qualified expressions [QualifiedExprUnsupported]
 // CHECK:STDERR: let T: type.not_found = {};
 // CHECK:STDERR:        ^~~~~~~~~~~~~~
 // CHECK:STDERR:
@@ -26,7 +26,7 @@ let T: type.not_found = {};
 
 library "[[@TEST_NAME]]";
 
-// CHECK:STDERR: fail_lookup_type_where.carbon:[[@LINE+4]]:8: error: member name `missing` not found [MemberNameNotFound]
+// CHECK:STDERR: fail_lookup_type_where.carbon:[[@LINE+4]]:8: error: type `type` does not support qualified expressions [QualifiedExprUnsupported]
 // CHECK:STDERR: let U: (type where .Self impls type).missing = {};
 // CHECK:STDERR:        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // CHECK:STDERR:
@@ -44,10 +44,7 @@ let U: (type where .Self impls type).missing = {};
 // CHECK:STDOUT:   package: <namespace> = namespace [concrete] {
 // CHECK:STDOUT:     .T = %T
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %.1: <error> = splice_block <error> [concrete = <error>] {
-// CHECK:STDOUT:     %.loc8: type = type_literal type [concrete = type]
-// CHECK:STDOUT:     %not_found.ref: <error> = name_ref not_found, <error> [concrete = <error>]
-// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %.loc8: type = type_literal type [concrete = type]
 // CHECK:STDOUT:   %T: <error> = wrapper_binding T, <error> [concrete = <error>]
 // CHECK:STDOUT:   name_binding_decl {
 // CHECK:STDOUT:     %T.patt: <error> = value_binding_pattern T [concrete = <error>]
@@ -88,7 +85,6 @@ let U: (type where .Self impls type).missing = {};
 // CHECK:STDOUT:       %base_facet_type = requirement_base_facet_type %.loc8_9 [concrete]
 // CHECK:STDOUT:       %impls.loc8_26.2 = requirement_impls %.Self.ref.loc8_20.2, %.loc8_32 [concrete]
 // CHECK:STDOUT:     }
-// CHECK:STDOUT:     %missing.ref: <error> = name_ref missing, <error> [concrete = <error>]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %U: <error> = wrapper_binding U, <error> [concrete = <error>]
 // CHECK:STDOUT:   name_binding_decl {