diff --git a/packages/flutter/lib/src/animation/tween.dart b/packages/flutter/lib/src/animation/tween.dart
index 3d002d76ed..1a909bb91d 100644
--- a/packages/flutter/lib/src/animation/tween.dart
+++ b/packages/flutter/lib/src/animation/tween.dart
@@ -75,6 +75,8 @@ class Tween<T extends dynamic> extends Animatable<T> {
       return end;
     return lerp(t);
   }
+
+  String toString() => '$runtimeType($begin \u2192 $end)';
 }
 
 /// An interpolation between two colors.
diff --git a/packages/flutter/lib/src/material/theme_data.dart b/packages/flutter/lib/src/material/theme_data.dart
index a9f87d55f7..f6a80bbb2a 100644
--- a/packages/flutter/lib/src/material/theme_data.dart
+++ b/packages/flutter/lib/src/material/theme_data.dart
@@ -285,5 +285,5 @@ class ThemeData {
     );
   }
 
-  String toString() => '$primaryColor $brightness etc...';
+  String toString() => '$runtimeType($brightness $primaryColor etc...)';
 }