diff --git a/example/reinforcement_learning/lib/main.dart b/example/reinforcement_learning/lib/main.dart
index c28b926..c37cb90 100644
--- a/example/reinforcement_learning/lib/main.dart
+++ b/example/reinforcement_learning/lib/main.dart
@@ -28,7 +28,7 @@ class PlaneStrike extends StatefulWidget {
 
   // This widget is the root of your application.
   @override
-  _PlaneStrikeState createState() => _PlaneStrikeState();
+  State<PlaneStrike> createState() => _PlaneStrikeState();
 }
 
 class _PlaneStrikeState extends State<PlaneStrike> {