diff --git a/packages/firebase_database/firebase_database/lib/ui/firebase_list.dart b/packages/firebase_database/firebase_database/lib/ui/firebase_list.dart
index 2d91c69c70fd..fcb26a5553d3 100644
--- a/packages/firebase_database/firebase_database/lib/ui/firebase_list.dart
+++ b/packages/firebase_database/firebase_database/lib/ui/firebase_list.dart
@@ -103,7 +103,7 @@ class FirebaseList extends ListBase<DataSnapshot>
       }
     }
 
-    throw FallThroughError();
+    throw UnsupportedError('Key not found: $key');
   }
 
   void _onChildAdded(DatabaseEvent event) {