diff --git a/firebase-get-to-know-flutter/codelab_rebuild.yaml b/firebase-get-to-know-flutter/codelab_rebuild.yaml
index 97859b2230..067128c762 100644
--- a/firebase-get-to-know-flutter/codelab_rebuild.yaml
+++ b/firebase-get-to-know-flutter/codelab_rebuild.yaml
@@ -2166,6 +2166,12 @@ steps:
                 ),
               );
             }
+          
+            @override
+            void dispose() {
+              _controller.dispose();
+              super.dispose();
+            }
           }
       - name: Patch lib/home_page.dart
         path: gtk_flutter/lib/home_page.dart
diff --git a/firebase-get-to-know-flutter/step_06/lib/guest_book.dart b/firebase-get-to-know-flutter/step_06/lib/guest_book.dart
index eb2e9a34b6..1a06c48abe 100644
--- a/firebase-get-to-know-flutter/step_06/lib/guest_book.dart
+++ b/firebase-get-to-know-flutter/step_06/lib/guest_book.dart
@@ -64,4 +64,10 @@ class _GuestBookState extends State<GuestBook> {
       ),
     );
   }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
 }
diff --git a/firebase-get-to-know-flutter/step_07/lib/guest_book.dart b/firebase-get-to-know-flutter/step_07/lib/guest_book.dart
index 011f50bec0..53d147a297 100644
--- a/firebase-get-to-know-flutter/step_07/lib/guest_book.dart
+++ b/firebase-get-to-know-flutter/step_07/lib/guest_book.dart
@@ -79,4 +79,10 @@ class _GuestBookState extends State<GuestBook> {
       ],
     );
   }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
 }
diff --git a/firebase-get-to-know-flutter/step_09/lib/guest_book.dart b/firebase-get-to-know-flutter/step_09/lib/guest_book.dart
index 011f50bec0..53d147a297 100644
--- a/firebase-get-to-know-flutter/step_09/lib/guest_book.dart
+++ b/firebase-get-to-know-flutter/step_09/lib/guest_book.dart
@@ -79,4 +79,10 @@ class _GuestBookState extends State<GuestBook> {
       ],
     );
   }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
 }