diff --git a/packages/pigeon/CHANGELOG.md b/packages/pigeon/CHANGELOG.md
index 988b465fb860..6cd489452156 100644
--- a/packages/pigeon/CHANGELOG.md
+++ b/packages/pigeon/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 9.1.2
+
+* [cpp] Fixes class parameters to Flutter APIs.
+
 ## 9.1.1
 
 * [swift] Removes experimental tags.
diff --git a/packages/pigeon/lib/cpp_generator.dart b/packages/pigeon/lib/cpp_generator.dart
index cae09fd932d7..7fa2b9e589c5 100644
--- a/packages/pigeon/lib/cpp_generator.dart
+++ b/packages/pigeon/lib/cpp_generator.dart
@@ -563,7 +563,8 @@ class CppSourceGenerator extends StructuredGenerator<CppOptions> {
         final HostDatatype hostDatatype = getFieldHostDatatype(field,
             root.classes, root.enums, _shortBaseCppTypeForBuiltinDartType);
         final String encodableValue = _wrappedHostApiArgumentExpression(
-            root, _makeInstanceVariableName(field), field.type, hostDatatype);
+            root, _makeInstanceVariableName(field), field.type, hostDatatype,
+            preSerializeClasses: true);
         indent.writeln('list.push_back($encodableValue);');
       }
       indent.writeln('return list;');
@@ -686,7 +687,8 @@ const flutter::StandardMessageCodec& ${api.name}::GetCodec() {
           indent.addScoped('EncodableValue(EncodableList{', '});', () {
             for (final _HostNamedType param in hostParameters) {
               final String encodedArgument = _wrappedHostApiArgumentExpression(
-                  root, param.name, param.originalType, param.hostType);
+                  root, param.name, param.originalType, param.hostType,
+                  preSerializeClasses: false);
               indent.writeln('$encodedArgument,');
             }
           });
@@ -994,14 +996,26 @@ ${prefix}reply(EncodableValue(std::move(wrapped)));''';
 
   /// Returns the expression to create an EncodableValue from a host API argument
   /// with the given [variableName] and types.
+  ///
+  /// If [preSerializeClasses] is true, custom classes will be returned as
+  /// encodable lists rather than CustomEncodableValues; see
+  /// https://github.com/flutter/flutter/issues/119351 for why this is currently
+  /// needed.
   String _wrappedHostApiArgumentExpression(Root root, String variableName,
-      TypeDeclaration dartType, HostDatatype hostType) {
+      TypeDeclaration dartType, HostDatatype hostType,
+      {required bool preSerializeClasses}) {
     final String encodableValue;
     if (!hostType.isBuiltin &&
         root.classes.any((Class c) => c.name == dartType.baseName)) {
-      final String operator = hostType.isNullable ? '->' : '.';
-      encodableValue =
-          'EncodableValue($variableName${operator}ToEncodableList())';
+      if (preSerializeClasses) {
+        final String operator = hostType.isNullable ? '->' : '.';
+        encodableValue =
+            'EncodableValue($variableName${operator}ToEncodableList())';
+      } else {
+        final String nonNullValue =
+            hostType.isNullable ? '*$variableName' : variableName;
+        encodableValue = 'CustomEncodableValue($nonNullValue)';
+      }
     } else if (!hostType.isBuiltin &&
         root.enums.any((Enum e) => e.name == dartType.baseName)) {
       final String nonNullValue =
diff --git a/packages/pigeon/lib/generator_tools.dart b/packages/pigeon/lib/generator_tools.dart
index d7d68b022a3c..236fac59fcdf 100644
--- a/packages/pigeon/lib/generator_tools.dart
+++ b/packages/pigeon/lib/generator_tools.dart
@@ -11,7 +11,7 @@ import 'ast.dart';
 /// The current version of pigeon.
 ///
 /// This must match the version in pubspec.yaml.
-const String pigeonVersion = '9.1.1';
+const String pigeonVersion = '9.1.2';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {
diff --git a/packages/pigeon/mock_handler_tester/test/message.dart b/packages/pigeon/mock_handler_tester/test/message.dart
index c710c5ad968d..626974d2f46b 100644
--- a/packages/pigeon/mock_handler_tester/test/message.dart
+++ b/packages/pigeon/mock_handler_tester/test/message.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
 
diff --git a/packages/pigeon/mock_handler_tester/test/test.dart b/packages/pigeon/mock_handler_tester/test/test.dart
index 7c40e2b00388..a4d3a6742617 100644
--- a/packages/pigeon/mock_handler_tester/test/test.dart
+++ b/packages/pigeon/mock_handler_tester/test/test.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, unnecessary_import
 // ignore_for_file: avoid_relative_lib_imports
diff --git a/packages/pigeon/platform_tests/alternate_language_test_plugin/android/src/main/java/com/example/alternate_language_test_plugin/CoreTests.java b/packages/pigeon/platform_tests/alternate_language_test_plugin/android/src/main/java/com/example/alternate_language_test_plugin/CoreTests.java
index 0413431f7cd1..74ce2594d6d9 100644
--- a/packages/pigeon/platform_tests/alternate_language_test_plugin/android/src/main/java/com/example/alternate_language_test_plugin/CoreTests.java
+++ b/packages/pigeon/platform_tests/alternate_language_test_plugin/android/src/main/java/com/example/alternate_language_test_plugin/CoreTests.java
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 package com.example.alternate_language_test_plugin;
diff --git a/packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/CoreTests.gen.h b/packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/CoreTests.gen.h
index 9015a67c4d0d..0b7afefaed4b 100644
--- a/packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/CoreTests.gen.h
+++ b/packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/CoreTests.gen.h
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 #import <Foundation/Foundation.h>
diff --git a/packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/CoreTests.gen.m b/packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/CoreTests.gen.m
index 5d5f72f2ed5b..ec21bed715dc 100644
--- a/packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/CoreTests.gen.m
+++ b/packages/pigeon/platform_tests/alternate_language_test_plugin/ios/Classes/CoreTests.gen.m
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 #import "CoreTests.gen.h"
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/core_tests.gen.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/core_tests.gen.dart
index 28113f78d334..ca65ee888626 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/core_tests.gen.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/core_tests.gen.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
 
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/flutter_unittests.gen.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/flutter_unittests.gen.dart
index 6c11b7454aee..48efd83103d5 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/flutter_unittests.gen.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/flutter_unittests.gen.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
 
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/multiple_arity.gen.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/multiple_arity.gen.dart
index bb236d263580..caadb893fa77 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/multiple_arity.gen.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/multiple_arity.gen.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
 
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/non_null_fields.gen.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/non_null_fields.gen.dart
index 840d8703e60c..5d84c9dc0ceb 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/non_null_fields.gen.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/non_null_fields.gen.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
 
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/null_fields.gen.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/null_fields.gen.dart
index 45d1b5ec14b4..77dd44c80a9d 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/null_fields.gen.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/null_fields.gen.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
 
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/nullable_returns.gen.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/nullable_returns.gen.dart
index 95af92032109..7a57cd1cfec1 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/nullable_returns.gen.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/nullable_returns.gen.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
 
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/primitive.gen.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/primitive.gen.dart
index 643125f7a219..f762999239ce 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/primitive.gen.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/primitive.gen.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
 
diff --git a/packages/pigeon/platform_tests/shared_test_plugin_code/lib/integration_tests.dart b/packages/pigeon/platform_tests/shared_test_plugin_code/lib/integration_tests.dart
index 9af7fc7932e3..5157041b0fc3 100644
--- a/packages/pigeon/platform_tests/shared_test_plugin_code/lib/integration_tests.dart
+++ b/packages/pigeon/platform_tests/shared_test_plugin_code/lib/integration_tests.dart
@@ -1112,10 +1112,7 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
       expect(listEquals(echoObject.aList, genericAllTypes.aList), true);
       expect(mapEquals(echoObject.aMap, genericAllTypes.aMap), true);
       expect(echoObject.anEnum, genericAllTypes.anEnum);
-    },
-        // TODO(stuartmorgan): Fix and re-enable.
-        // See https://github.com/flutter/flutter/issues/118739
-        skip: targetGenerator == TargetGenerator.cpp);
+    });
 
     testWidgets(
         'Arguments of multiple types serialize and deserialize correctly',
diff --git a/packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/core_tests.gen.dart b/packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/core_tests.gen.dart
index 28113f78d334..ca65ee888626 100644
--- a/packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/core_tests.gen.dart
+++ b/packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/core_tests.gen.dart
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import
 
diff --git a/packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/CoreTests.gen.kt b/packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/CoreTests.gen.kt
index 2fe1dbd9b0f2..7b02c87e311e 100644
--- a/packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/CoreTests.gen.kt
+++ b/packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/CoreTests.gen.kt
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 // 
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 package com.example.test_plugin
diff --git a/packages/pigeon/platform_tests/test_plugin/ios/Classes/CoreTests.gen.swift b/packages/pigeon/platform_tests/test_plugin/ios/Classes/CoreTests.gen.swift
index dc9087460e58..4ffca877b55f 100644
--- a/packages/pigeon/platform_tests/test_plugin/ios/Classes/CoreTests.gen.swift
+++ b/packages/pigeon/platform_tests/test_plugin/ios/Classes/CoreTests.gen.swift
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 // 
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 import Foundation
diff --git a/packages/pigeon/platform_tests/test_plugin/macos/Classes/CoreTests.gen.swift b/packages/pigeon/platform_tests/test_plugin/macos/Classes/CoreTests.gen.swift
index dc9087460e58..4ffca877b55f 100644
--- a/packages/pigeon/platform_tests/test_plugin/macos/Classes/CoreTests.gen.swift
+++ b/packages/pigeon/platform_tests/test_plugin/macos/Classes/CoreTests.gen.swift
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 // 
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 import Foundation
diff --git a/packages/pigeon/platform_tests/test_plugin/windows/pigeon/core_tests.gen.cpp b/packages/pigeon/platform_tests/test_plugin/windows/pigeon/core_tests.gen.cpp
index d2002353e719..a9df10cf4c11 100644
--- a/packages/pigeon/platform_tests/test_plugin/windows/pigeon/core_tests.gen.cpp
+++ b/packages/pigeon/platform_tests/test_plugin/windows/pigeon/core_tests.gen.cpp
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 #undef _HAS_EXCEPTIONS
@@ -3130,7 +3130,7 @@ void FlutterIntegrationCoreApi::EchoAllTypes(
       binary_messenger_,
       "dev.flutter.pigeon.FlutterIntegrationCoreApi.echoAllTypes", &GetCodec());
   EncodableValue encoded_api_arguments = EncodableValue(EncodableList{
-      EncodableValue(everything_arg.ToEncodableList()),
+      CustomEncodableValue(everything_arg),
   });
   channel->Send(
       encoded_api_arguments,
@@ -3153,7 +3153,7 @@ void FlutterIntegrationCoreApi::EchoAllNullableTypes(
       "dev.flutter.pigeon.FlutterIntegrationCoreApi.echoAllNullableTypes",
       &GetCodec());
   EncodableValue encoded_api_arguments = EncodableValue(EncodableList{
-      EncodableValue(everything_arg.ToEncodableList()),
+      CustomEncodableValue(everything_arg),
   });
   channel->Send(
       encoded_api_arguments,
@@ -3718,7 +3718,7 @@ void FlutterSmallApi::EchoWrappedList(
       binary_messenger_, "dev.flutter.pigeon.FlutterSmallApi.echoWrappedList",
       &GetCodec());
   EncodableValue encoded_api_arguments = EncodableValue(EncodableList{
-      EncodableValue(msg_arg.ToEncodableList()),
+      CustomEncodableValue(msg_arg),
   });
   channel->Send(
       encoded_api_arguments,
diff --git a/packages/pigeon/platform_tests/test_plugin/windows/pigeon/core_tests.gen.h b/packages/pigeon/platform_tests/test_plugin/windows/pigeon/core_tests.gen.h
index fd5975c52049..a4d6de76fb2a 100644
--- a/packages/pigeon/platform_tests/test_plugin/windows/pigeon/core_tests.gen.h
+++ b/packages/pigeon/platform_tests/test_plugin/windows/pigeon/core_tests.gen.h
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Autogenerated from Pigeon (v9.1.1), do not edit directly.
+// Autogenerated from Pigeon (v9.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 #ifndef PIGEON_CORE_TESTS_GEN_H_
diff --git a/packages/pigeon/pubspec.yaml b/packages/pigeon/pubspec.yaml
index c38c2f72b804..ef999c579985 100644
--- a/packages/pigeon/pubspec.yaml
+++ b/packages/pigeon/pubspec.yaml
@@ -2,7 +2,7 @@ name: pigeon
 description: Code generator tool to make communication between Flutter and the host platform type-safe and easier.
 repository: https://github.com/flutter/packages/tree/main/packages/pigeon
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3Apigeon
-version: 9.1.1 # This must match the version in lib/generator_tools.dart
+version: 9.1.2 # This must match the version in lib/generator_tools.dart
 
 environment:
   sdk: ">=2.17.0 <4.0.0"
diff --git a/packages/pigeon/test/cpp_generator_test.dart b/packages/pigeon/test/cpp_generator_test.dart
index 36cb00759e02..10652b251bf5 100644
--- a/packages/pigeon/test/cpp_generator_test.dart
+++ b/packages/pigeon/test/cpp_generator_test.dart
@@ -1312,7 +1312,7 @@ void main() {
       expect(
           code,
           contains(
-              'an_object_arg ? EncodableValue(an_object_arg->ToEncodableList()) : EncodableValue()'));
+              'an_object_arg ? CustomEncodableValue(*an_object_arg) : EncodableValue()'));
     }
   });
 
@@ -1433,7 +1433,7 @@ void main() {
       expect(code, contains('EncodableValue(a_list_arg)'));
       expect(code, contains('EncodableValue(a_map_arg)'));
       // Class types use ToEncodableList.
-      expect(code, contains('EncodableValue(an_object_arg.ToEncodableList())'));
+      expect(code, contains('CustomEncodableValue(an_object_arg)'));
     }
   });