diff --git a/packages/flutter/test/services/default_binary_messenger_test.dart b/packages/flutter/test/services/default_binary_messenger_test.dart
index 4ce14e82bf..9d26f60d99 100644
--- a/packages/flutter/test/services/default_binary_messenger_test.dart
+++ b/packages/flutter/test/services/default_binary_messenger_test.dart
@@ -51,7 +51,7 @@ void main() {
   });
 
   test('can check the mock handler', () {
-    Future<ByteData> handler(ByteData? call) => Future<ByteData>.value(null);
+    Future<ByteData?> handler(ByteData? call) => Future<ByteData?>.value(null);
     final TestDefaultBinaryMessenger messenger = TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger;
 
     expect(messenger.checkMockMessageHandler('test_channel', null), true);