diff --git a/lib/Page.js b/lib/Page.js
index 54a8383c..c507c03a 100644
--- a/lib/Page.js
+++ b/lib/Page.js
@@ -78,6 +78,7 @@ class Page extends EventEmitter {
     this._keyboard = new Keyboard(client);
     this._mouse = new Mouse(client, this._keyboard);
     this._touchscreen = new Touchscreen(client, this._keyboard);
+    /** @type {!FrameManager} */
     this._frameManager = new FrameManager(client, frameTree, this);
     this._networkManager = new NetworkManager(client, this._frameManager);
     this._emulationManager = new EmulationManager(client);