diff --git a/lib/index.d.ts b/lib/index.d.ts
index 2374d10371..27c48bb1ab 100644
--- a/lib/index.d.ts
+++ b/lib/index.d.ts
@@ -613,7 +613,7 @@ export namespace FirebaseMessagingTypes {
      *
      * @param listener Called with a `RemoteMessage` when a notification press opens the application.
      */
-    onNotificationOpenedApp(listener: (message: RemoteMessage) => any): void;
+    onNotificationOpenedApp(listener: (message: RemoteMessage) => any): () => void;
 
     /**
      * Called when a new registration token is generated for the device. For example, this event can happen when a