diff --git a/browser/components/customizableui/content/panelUI.js b/browser/components/customizableui/content/panelUI.js
index 5865b94feb1..58249f6cdfe 100644
--- a/browser/components/customizableui/content/panelUI.js
+++ b/browser/components/customizableui/content/panelUI.js
@@ -56,6 +56,10 @@ const PanelUI = {
   },
 
   uninit: function() {
+    if (!this._eventListenersAdded) {
+      return;
+    }
+
     for (let event of this.kEvents) {
       this.panel.removeEventListener(event, this);
     }