diff --git a/tests/unit/test_patch_scope.py b/tests/unit/test_patch_scope.py
index fc533bf4..42316d68 100644
--- a/tests/unit/test_patch_scope.py
+++ b/tests/unit/test_patch_scope.py
@@ -100,6 +100,10 @@ def _getmembers(obj):
     monkeypatch.setattr(
         triton_frontend.tl.core, "is_builtin", lambda member: member is sentinel
     )
+    # The frontend caches each object's builtin names on first use; under the
+    # fake getmembers it would cache almost none, and every later unpatch_lang
+    # in the process would then leave triton.language patched.
+    monkeypatch.setattr(triton_frontend.frontend, "_triton_builtin_attr_cache", {})
 
     scope = triton_frontend.frontend._triton_snapshot_scope(_dummy_kernel)
     replacement = lambda *_args, **_kwargs: None