diff --git a/browser/base/content/test/general/browser_accesskeys.js b/browser/base/content/test/general/browser_accesskeys.js
index 1515eb690630..ec9a344750ab 100644
--- a/browser/base/content/test/general/browser_accesskeys.js
+++ b/browser/base/content/test/general/browser_accesskeys.js
@@ -32,6 +32,8 @@ add_task(async function() {
 
   Services.focus.clearFocus(window);
 
+  newButton.getBoundingClientRect(); // Accesskey registration happens during frame construction.
+
   focusedId = await performAccessKeyForChrome("z");
   is(focusedId, "chromebutton", "chromebutton accesskey");