--- a/mobile/android/components/SessionStore.js
+++ b/mobile/android/components/SessionStore.js
@@ -1,11 +1,12 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
 
 const Cc = Components.classes;
 const Ci = Components.interfaces;
 const Cu = Components.utils;
 const Cr = Components.results;
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Services.jsm");
@@ -195,20 +196,21 @@ SessionStore.prototype = {
         observerService.addObserver(this, "Tabs:OpenMultiple", true);
         break;
       case "final-ui-startup":
         observerService.removeObserver(this, "final-ui-startup");
         this.init();
         break;
       case "domwindowopened": {
         let window = aSubject;
-        window.addEventListener("load", () => {
+        let onLoad = () => {
+          window.removeEventListener("load", onLoad);
           this.onWindowOpen(window);
-          window.removeEventListener("load", arguments.callee);
-        });
+        };
+        window.addEventListener("load", onLoad);
         break;
       }
       case "domwindowclosed": // catch closed windows
         this.onWindowClose(aSubject);
         break;
       case "quit-application-requested":
         log("quit-application-requested");
         // Get a current snapshot of all windows