diff --git a/happydom.ts b/happydom.ts
index a51cee6..984722e 100644
--- a/happydom.ts
+++ b/happydom.ts
@@ -1,4 +1,8 @@
 import { GlobalRegistrator } from "@happy-dom/global-registrator";
+import { mock } from "bun:test";
 
 GlobalRegistrator.register();
-Object.assign(global, require('jest-chrome'))
\ No newline at end of file
+Object.assign(global, require('jest-chrome'))
+
+// Mock GM_fetch
+globalThis.GM_fetch = mock(async () => {});