diff --git a/dev/integration_tests/ui/lib/driver.dart b/dev/integration_tests/ui/lib/driver.dart
index b4625518ba..f21e9bfd85 100644
--- a/dev/integration_tests/ui/lib/driver.dart
+++ b/dev/integration_tests/ui/lib/driver.dart
@@ -7,7 +7,10 @@ import 'package:flutter/widgets.dart';
 import 'package:flutter_driver/driver_extension.dart';
 
 void main() {
-  enableFlutterDriverExtension();
+  enableFlutterDriverExtension(handler: (String message) async {
+    // TODO(cbernaschina) remove when test flakiness is resolved
+    return 'driver';
+  });
   runApp(new DriverTestApp());
 }
 
diff --git a/dev/integration_tests/ui/lib/keyboard_resize.dart b/dev/integration_tests/ui/lib/keyboard_resize.dart
index d961f35574..9e6a9a9851 100644
--- a/dev/integration_tests/ui/lib/keyboard_resize.dart
+++ b/dev/integration_tests/ui/lib/keyboard_resize.dart
@@ -8,7 +8,10 @@ import 'package:flutter_driver/driver_extension.dart';
 import 'keys.dart' as keys;
 
 void main() {
-  enableFlutterDriverExtension();
+  enableFlutterDriverExtension(handler: (String message) async {
+    // TODO(cbernaschina) remove when test flakiness is resolved
+    return 'keyboard_resize';
+  });
   runApp(new MyApp());
 }
 
diff --git a/packages/flutter_driver/lib/src/extension.dart b/packages/flutter_driver/lib/src/extension.dart
index 5f7e4cf4bb..36218e8cba 100644
--- a/packages/flutter_driver/lib/src/extension.dart
+++ b/packages/flutter_driver/lib/src/extension.dart
@@ -324,7 +324,7 @@ class FlutterDriverExtension {
 
   Future<RequestDataResult> _requestData(Command command) async {
     final RequestData requestDataCommand = command;
-    return new RequestDataResult(_requestDataHandler == null ? '' : await _requestDataHandler(requestDataCommand.message));
+    return new RequestDataResult(_requestDataHandler == null ? 'No requestData Extension registered' : await _requestDataHandler(requestDataCommand.message));
   }
 
   Future<SetFrameSyncResult> _setFrameSync(Command command) async {