diff --git a/packages/flutter/lib/src/widgets/framework.dart b/packages/flutter/lib/src/widgets/framework.dart
index dd7f698063..b902e551c9 100644
--- a/packages/flutter/lib/src/widgets/framework.dart
+++ b/packages/flutter/lib/src/widgets/framework.dart
@@ -304,9 +304,6 @@ abstract class Widget {
   }
 }
 
-/// The signature of build() functions.
-typedef Widget _BuildFunction(BuildContext context);
-
 /// StatelessWidgets describe a way to compose other Widgets to form reusable
 /// parts, which doesn't depend on anything other than the configuration
 /// information in the object itself. (For compositions that can change
@@ -331,7 +328,7 @@ abstract class StatelessWidget extends Widget {
   Widget build(BuildContext context);
 
   /// Trampoline to make the [build] closure library-accessible.
-  _BuildFunction get _build => build;
+  WidgetBuilder get _build => build;
 }
 
 /// StatefulWidgets provide the configuration for
@@ -491,7 +488,7 @@ abstract class State<T extends StatefulWidget> {
   Widget build(BuildContext context);
 
   /// Trampoline to make the [build] closure library-accessible.
-  _BuildFunction get _build => build;
+  WidgetBuilder get _build => build;
 
   /// Called when an Inherited widget in the ancestor chain has changed. Usually
   /// there is nothing to do here; whenever this is called, build() is also