diff --git a/devtools/startup/DevToolsStartup.sys.mjs b/devtools/startup/DevToolsStartup.sys.mjs
index ab008a13b4a6a31b18d5587e93e1ff589693cdac..946d1c70600fcfda5452d130dd1924c92d502562 100644
--- a/devtools/startup/DevToolsStartup.sys.mjs
+++ b/devtools/startup/DevToolsStartup.sys.mjs
@@ -836,6 +836,9 @@ export class DevToolsStartup {
     // account (see bug 832984).
     const mainKeyset = doc.getElementById("mainKeyset");
     mainKeyset.parentNode.insertBefore(keyset, mainKeyset);
+    mainKeyset.documentGlobal.setTimeout(() => {
+      window.dispatchEvent(new window.Event("zen-devtools-keyset-added"));
+    }, 0);
   }
 
   /**
