diff --git a/js/ui/layout.js b/js/ui/layout.js
index 9024695db..12717091c 100644
--- a/js/ui/layout.js
+++ b/js/ui/layout.js
@@ -362,7 +362,7 @@ const LayoutManager = new Lang.Class({
                               BackgroundMenu.addBackgroundMenu(bgManager.background.actor);
                           }));
 
-        this._bgManagers.push(bgManager);
+        this._bgManagers[monitorIndex] = bgManager;
 
         return bgManager.background;
     },