diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index 1adaf39a8..e7c342a84 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -1491,7 +1491,7 @@ vAPI.toolbarButton.init = function() {
         );
     } else {
         this.CUIEvents = {};
-        this.CUIEvents.updateBadge = function() {
+        var updateBadge = function() {
             var wId = vAPI.toolbarButton.id;
             var buttonInPanel = CustomizableUI.getWidget(wId).areaType === CustomizableUI.TYPE_MENU_PANEL;
 
@@ -1513,9 +1513,9 @@ vAPI.toolbarButton.init = function() {
 
             // Anonymous elements need some time to be reachable
             setTimeout(this.updateBadgeStyle, 250);
-        };
-        this.CUIEvents.onCustomizeEnd = this.CUIEvents.updateBadge;
-        this.CUIEvents.onWidgetUnderflow = this.CUIEvents.updateBadge;
+        }.bind(this.CUIEvents);
+        this.CUIEvents.onCustomizeEnd = updateBadge;
+        this.CUIEvents.onWidgetUnderflow = updateBadge;
 
         this.CUIEvents.updateBadgeStyle = function() {
             var css = [
@@ -1543,7 +1543,7 @@ vAPI.toolbarButton.init = function() {
 
         this.onCreated = function(button) {
             button.setAttribute('badge', '');
-            setTimeout(this.CUIEvents.updateBadge, 250);
+            setTimeout(updateBadge, 250);
         };
 
         CustomizableUI.addListener(this.CUIEvents);