diff --git a/packages/flutter/lib/src/widgets/transitions.dart b/packages/flutter/lib/src/widgets/transitions.dart
index cd458bd589..a46fb8283a 100644
--- a/packages/flutter/lib/src/widgets/transitions.dart
+++ b/packages/flutter/lib/src/widgets/transitions.dart
@@ -35,6 +35,7 @@ abstract class AnimatedWidget extends StatefulWidget {
 
   /// Override this method to build widgets that depend on the current value
   /// of the animation.
+  @protected
   Widget build(BuildContext context);
 
   /// Subclasses typically do not override this method.