diff --git a/frontend/tests/setup.ts b/frontend/tests/setup.ts
index 2d2e71b..9282432 100644
--- a/frontend/tests/setup.ts
+++ b/frontend/tests/setup.ts
@@ -1,7 +1,7 @@
 import '@testing-library/jest-dom/vitest';
 
 // jsdom doesn't implement ResizeObserver; provide a no-op stub for tests.
-global.ResizeObserver = class ResizeObserver {
+globalThis.ResizeObserver = class ResizeObserver {
   observe() {}
   unobserve() {}
   disconnect() {}