diff --git a/testing/web-platform/meta/animation-worklet/idlharness.any.js.ini b/testing/web-platform/meta/animation-worklet/idlharness.any.js.ini
index 4d84d5aeb74d..8fbade07865a 100644
--- a/testing/web-platform/meta/animation-worklet/idlharness.any.js.ini
+++ b/testing/web-platform/meta/animation-worklet/idlharness.any.js.ini
@@ -73,3 +73,6 @@
   [WorkletAnimation interface: new WorkletAnimation("name") must not have property "animatorName"]
     expected: FAIL
 
+  [WorkletAnimation interface: new WorkletAnimation("name") must not have property "undefined"]
+    expected: FAIL
+