diff --git a/selfdrive/car/tests/test_models.py b/selfdrive/car/tests/test_models.py
index 0b07213178..8fd1dc3ab6 100755
--- a/selfdrive/car/tests/test_models.py
+++ b/selfdrive/car/tests/test_models.py
@@ -49,6 +49,7 @@ def load_test_cases_from_file(file_path):
 # build list of test cases
 test_cases: List[Tuple[str, Optional[CarTestRoute]]] = []
 if len(INTERNAL_SEG_LIST):
+  # run with pytest -n32 --dist=loadscope, URLFile's caching isn't thread safe
   test_cases = load_test_cases_from_file(INTERNAL_SEG_LIST)
 else:
   routes_by_car = defaultdict(set)