diff --git a/packages/animations/lib/src/open_container.dart b/packages/animations/lib/src/open_container.dart
index bec071c..24523ec 100644
--- a/packages/animations/lib/src/open_container.dart
+++ b/packages/animations/lib/src/open_container.dart
@@ -342,10 +342,10 @@
 class _Hideable extends StatefulWidget {
   const _Hideable({
     Key? key,
-    this.child,
+    required this.child,
   }) : super(key: key);
 
-  final Widget? child;
+  final Widget child;
 
   @override
   State<_Hideable> createState() => _HideableState();