diff --git a/browser/metro/base/content/browser.xul b/browser/metro/base/content/browser.xul
index d25f4aa41edc..9ea297eff0af 100644
--- a/browser/metro/base/content/browser.xul
+++ b/browser/metro/base/content/browser.xul
@@ -403,7 +403,7 @@
         <deck id="updateDeck" orient="vertical">
           <hbox id="updateButtonBox" align="center">
             <button id="updateButton" align="start"
-                    oncommand="gAppUpdater.buttonOnCommand();"/>
+                    oncommand="FlyoutPanelsUI.AboutFlyout.appUpdater.buttonOnCommand();"/>
             <spacer flex="1"/>
           </hbox>
           <hbox id="checkingForUpdates" align="center">
diff --git a/browser/metro/base/content/flyouts/aboutFlyout.js b/browser/metro/base/content/flyouts/aboutFlyout.js
index b70c761f79f0..e4418994ad09 100644
--- a/browser/metro/base/content/flyouts/aboutFlyout.js
+++ b/browser/metro/base/content/flyouts/aboutFlyout.js
@@ -52,7 +52,8 @@ let AboutFlyout = {
       case 'MozFlyoutPanelShowing':
 #ifdef MOZ_UPDATER
         onUnload();
-        gAppUpdater = new appUpdater();
+        this.appUpdater = new appUpdater();
+        gAppUpdater = this.appUpdater;
 #endif
         break;
     }
@@ -74,6 +75,7 @@ function onUnload(aEvent) {
   // Safe to call even when there isn't a download in progress.
   gAppUpdater.removeDownloadListener();
   gAppUpdater = null;
+  AboutFlyout.appUpdater = null;
 }
 
 function appUpdater()
@@ -547,7 +549,7 @@ appUpdater.prototype =
         this.selectPanel("applying");
         let update = this.um.activeUpdate;
         let self = this;
-        Services.obs.addObserver(function (aSubject, aTopic, aData) {
+        Services.obs.addObserver(function updateStaged(aSubject, aTopic, aData) {
           // Update the UI when the background updater is finished
           let status = aData;
           if (status == "applied" || status == "applied-service" ||
@@ -569,7 +571,7 @@ appUpdater.prototype =
             self.setupDownloadingUI();
             return;
           }
-          Services.obs.removeObserver(arguments.callee, "update-staged");
+          Services.obs.removeObserver(updateStaged, "update-staged");
         }, "update-staged", false);
       } else {
         this.selectPanel("updateButtonBox");