--- a/browser/components/customizableui/test/browser_widget_animation.js
+++ b/browser/components/customizableui/test/browser_widget_animation.js
@@ -22,35 +22,33 @@ function promiseWidgetAnimationOut(aNode
   });
 }
 
 function promiseOverflowAnimationEnd() {
   return new Promise(resolve => {
     let overflowButton = document.getElementById("nav-bar-overflow-button");
     overflowButton.addEventListener("animationend", function cleanupOverflowAnimationOut(event) {
       if (event.animationName == "overflow-fade") {
-        overflowButton.removeEventListener("transitionend", cleanupOverflowAnimationOut);
+        overflowButton.removeEventListener("animationend", cleanupOverflowAnimationOut);
         ok(true, "The overflow button`s animationend event should have happened");
         resolve();
       }
     });
   });
 }
 
 // Right-click on the home widget, use the context menu to move it to the overflow menu.
 // The home widget should animate out, and the overflow menu should animate upon adding.
 add_task(async function() {
   let homeButton = document.getElementById("home-button");
   let contextMenu = document.getElementById("toolbar-context-menu");
   let shownPromise = popupShown(contextMenu);
   EventUtils.synthesizeMouseAtCenter(homeButton, {type: "contextmenu", button: 2 });
   await shownPromise;
 
-  let moveToPanel = contextMenu.querySelector(".customize-context-moveToPanel");
-  if (moveToPanel) {
-    moveToPanel.click();
-  }
+  contextMenu.querySelector(".customize-context-moveToPanel").click();
+  await contextMenu.hidePopup();
 
   await Promise.all([promiseWidgetAnimationOut(homeButton), promiseOverflowAnimationEnd()]);
   ok(true, "The widget and overflow animations should have both happened.");
 });
 
 registerCleanupFunction(CustomizableUI.reset);