diff --git a/packages/flutter/lib/src/widgets/banner.dart b/packages/flutter/lib/src/widgets/banner.dart
index 5f2dd73f14..2ad3bb58d8 100644
--- a/packages/flutter/lib/src/widgets/banner.dart
+++ b/packages/flutter/lib/src/widgets/banner.dart
@@ -162,6 +162,7 @@ class Banner extends StatelessWidget {
 }
 
 /// Displays a [Banner] saying "SLOW MODE" when running in checked mode.
+/// [MaterialApp] builds one of these by default.
 /// Does nothing in release mode.
 class CheckedModeBanner extends StatelessWidget {
   /// Creates a checked mode banner.