diff --git a/toolchain/check/cpp/thunk.cpp b/toolchain/check/cpp/thunk.cpp
index 251af0483a52..6a53e3b592f6 100644
--- a/toolchain/check/cpp/thunk.cpp
+++ b/toolchain/check/cpp/thunk.cpp
@@ -669,9 +669,25 @@ auto PerformCppThunkCall(Context& context, SemIR::LocId loc_id,
                           context.insts().Get(return_slot_id).type_id())),
          .lvalue_id = return_slot_id});
     thunk_arg_ids.push_back(arg_id);
+  } else if (return_slot_id.has_value()) {
+    thunk_arg_ids.push_back(return_slot_id);
   }
 
-  auto result_id = PerformCall(context, loc_id, thunk_callee_id, thunk_arg_ids);
+  // Compute the return type of the call to the thunk.
+  auto thunk_return_type_id =
+      thunk_function.GetDeclaredReturnType(context.sem_ir());
+  if (!thunk_return_type_id.has_value()) {
+    CARBON_CHECK(thunk_takes_return_address || !return_type_id.has_value());
+    thunk_return_type_id = GetTupleType(context, {});
+  } else {
+    CARBON_CHECK(thunk_return_type_id == return_type_id);
+  }
+
+  auto result_id = GetOrAddInst<SemIR::Call>(
+      context, loc_id,
+      {.type_id = thunk_return_type_id,
+       .callee_id = thunk_callee_id,
+       .args_id = context.inst_blocks().Add(thunk_arg_ids)});
 
   // Produce the result of the call, taking the value from the return storage.
   if (thunk_takes_return_address) {
diff --git a/toolchain/check/testdata/interop/cpp/function/pointer.carbon b/toolchain/check/testdata/interop/cpp/function/pointer.carbon
index dc844d5ec832..af7024e80931 100644
--- a/toolchain/check/testdata/interop/cpp/function/pointer.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/pointer.carbon
@@ -1036,9 +1036,8 @@ fn F() {
 // CHECK:STDOUT:   %.loc11_14.2: init %Optional.143 = converted %addr.loc11_14.1, %T.binding.as_type.as.ImplicitAs.impl.Convert.call
 // CHECK:STDOUT:   %.loc11_14.3: ref %Optional.143 = temporary %.loc11_14.1, %.loc11_14.2
 // CHECK:STDOUT:   %.loc11_14.4: %Optional.143 = bind_value %.loc11_14.3
-// CHECK:STDOUT:   %.loc11_16.2: ref %Optional.143 = temporary_storage
-// CHECK:STDOUT:   %Direct__carbon_thunk.call: init %Optional.143 = call imports.%Direct__carbon_thunk.decl(%.loc11_14.4) to %.loc11_16.2
-// CHECK:STDOUT:   %.loc11_16.3: ref %Optional.143 = temporary %.loc11_16.2, %Direct__carbon_thunk.call
+// CHECK:STDOUT:   %Direct__carbon_thunk.call: init %Optional.143 = call imports.%Direct__carbon_thunk.decl(%.loc11_14.4) to %.loc11_16.1
+// CHECK:STDOUT:   %.loc11_16.2: ref %Optional.143 = temporary %.loc11_16.1, %Direct__carbon_thunk.call
 // CHECK:STDOUT:   name_binding_decl {
 // CHECK:STDOUT:     %a.patt: %pattern_type.aa5 = value_binding_pattern a [concrete]
 // CHECK:STDOUT:   }
@@ -1055,8 +1054,7 @@ fn F() {
 // CHECK:STDOUT:   %.loc13_50.2: %S = bind_value %.loc13_50.1
 // CHECK:STDOUT:   %.loc13_50.3: ref %S = value_as_ref %.loc13_50.2
 // CHECK:STDOUT:   %addr.loc13_58.1: %ptr.5c7 = addr_of %.loc13_50.3
-// CHECK:STDOUT:   %.loc13_58.2: ref %Optional.143 = temporary_storage
-// CHECK:STDOUT:   %Indirect__carbon_thunk.call: init %Optional.143 = call imports.%Indirect__carbon_thunk.decl(%addr.loc13_58.1) to %.loc13_58.2
+// CHECK:STDOUT:   %Indirect__carbon_thunk.call: init %Optional.143 = call imports.%Indirect__carbon_thunk.decl(%addr.loc13_58.1) to %.loc13_58.1
 // CHECK:STDOUT:   %.loc13_30.1: type = splice_block %Optional [concrete = constants.%Optional.143] {
 // CHECK:STDOUT:     %Core.ref: <namespace> = name_ref Core, imports.%Core [concrete = imports.%Core]
 // CHECK:STDOUT:     %Optional.ref: %Optional.type = name_ref Optional, imports.%Core.Optional [concrete = constants.%Optional.generic]
@@ -1067,23 +1065,23 @@ fn F() {
 // CHECK:STDOUT:     %.loc13_30.2: %OptionalStorage.type = converted %ptr, %OptionalStorage.facet [concrete = constants.%OptionalStorage.facet]
 // CHECK:STDOUT:     %Optional: type = class_type @Optional, @Optional(constants.%OptionalStorage.facet) [concrete = constants.%Optional.143]
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %.loc13_58.3: ref %Optional.143 = temporary %.loc13_58.2, %Indirect__carbon_thunk.call
-// CHECK:STDOUT:   %.loc13_58.4: %Optional.143 = bind_value %.loc13_58.3
-// CHECK:STDOUT:   %a: %Optional.143 = value_binding a, %.loc13_58.4
-// CHECK:STDOUT:   %DestroyT.binding.as_type.as.Destroy.impl.Op.bound.loc13_58: <bound method> = bound_method %.loc13_58.3, constants.%DestroyT.binding.as_type.as.Destroy.impl.Op.465
+// CHECK:STDOUT:   %.loc13_58.2: ref %Optional.143 = temporary %.loc13_58.1, %Indirect__carbon_thunk.call
+// CHECK:STDOUT:   %.loc13_58.3: %Optional.143 = bind_value %.loc13_58.2
+// CHECK:STDOUT:   %a: %Optional.143 = value_binding a, %.loc13_58.3
+// CHECK:STDOUT:   %DestroyT.binding.as_type.as.Destroy.impl.Op.bound.loc13_58: <bound method> = bound_method %.loc13_58.2, constants.%DestroyT.binding.as_type.as.Destroy.impl.Op.465
 // CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %bound_method.loc13_58: <bound method> = bound_method %.loc13_58.3, %DestroyT.binding.as_type.as.Destroy.impl.Op.specific_fn.1
-// CHECK:STDOUT:   %addr.loc13_58.2: %ptr.451 = addr_of %.loc13_58.3
+// CHECK:STDOUT:   %bound_method.loc13_58: <bound method> = bound_method %.loc13_58.2, %DestroyT.binding.as_type.as.Destroy.impl.Op.specific_fn.1
+// CHECK:STDOUT:   %addr.loc13_58.2: %ptr.451 = addr_of %.loc13_58.2
 // CHECK:STDOUT:   %DestroyT.binding.as_type.as.Destroy.impl.Op.call.loc13_58: init %empty_tuple.type = call %bound_method.loc13_58(%addr.loc13_58.2)
 // CHECK:STDOUT:   %DestroyT.binding.as_type.as.Destroy.impl.Op.bound.loc13_48: <bound method> = bound_method %.loc13_48.4, constants.%DestroyT.binding.as_type.as.Destroy.impl.Op.016
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %bound_method.loc13_48: <bound method> = bound_method %.loc13_48.4, %DestroyT.binding.as_type.as.Destroy.impl.Op.specific_fn.2
 // CHECK:STDOUT:   %addr.loc13_48: %ptr.5c7 = addr_of %.loc13_48.4
 // CHECK:STDOUT:   %DestroyT.binding.as_type.as.Destroy.impl.Op.call.loc13_48: init %empty_tuple.type = call %bound_method.loc13_48(%addr.loc13_48)
-// CHECK:STDOUT:   %DestroyT.binding.as_type.as.Destroy.impl.Op.bound.loc11_16: <bound method> = bound_method %.loc11_16.3, constants.%DestroyT.binding.as_type.as.Destroy.impl.Op.465
+// CHECK:STDOUT:   %DestroyT.binding.as_type.as.Destroy.impl.Op.bound.loc11_16: <bound method> = bound_method %.loc11_16.2, constants.%DestroyT.binding.as_type.as.Destroy.impl.Op.465
 // CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %bound_method.loc11_16: <bound method> = bound_method %.loc11_16.3, %DestroyT.binding.as_type.as.Destroy.impl.Op.specific_fn.3
-// CHECK:STDOUT:   %addr.loc11_16: %ptr.451 = addr_of %.loc11_16.3
+// CHECK:STDOUT:   %bound_method.loc11_16: <bound method> = bound_method %.loc11_16.2, %DestroyT.binding.as_type.as.Destroy.impl.Op.specific_fn.3
+// CHECK:STDOUT:   %addr.loc11_16: %ptr.451 = addr_of %.loc11_16.2
 // CHECK:STDOUT:   %DestroyT.binding.as_type.as.Destroy.impl.Op.call.loc11_16: init %empty_tuple.type = call %bound_method.loc11_16(%addr.loc11_16)
 // CHECK:STDOUT:   %DestroyT.binding.as_type.as.Destroy.impl.Op.bound.loc11_14: <bound method> = bound_method %.loc11_14.3, constants.%DestroyT.binding.as_type.as.Destroy.impl.Op.465
 // CHECK:STDOUT:   <elided>