diff --git a/packages/flutter/lib/src/fn3/scrollable.dart b/packages/flutter/lib/src/fn3/scrollable.dart
index 8e582088c2..214227bbd4 100644
--- a/packages/flutter/lib/src/fn3/scrollable.dart
+++ b/packages/flutter/lib/src/fn3/scrollable.dart
@@ -128,7 +128,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
   bool _scrollOffsetIsInBounds(double offset) {
     if (scrollBehavior is! ExtentScrollBehavior)
       return false;
-    ExtentScrollBehavior behavior = scrollBehavior as ExtentScrollBehavior;
+    ExtentScrollBehavior behavior = scrollBehavior;
     return offset >= behavior.minScrollOffset && offset < behavior.maxScrollOffset;
   }