diff --git a/tests/functional/test_reflector.py b/tests/functional/test_reflector.py
index 43db60bd5..201099998 100644
--- a/tests/functional/test_reflector.py
+++ b/tests/functional/test_reflector.py
@@ -49,6 +49,7 @@ class TestReflector(unittest.TestCase):
                 raise unittest.SkipTest("TODO: fix this for windows")
 
         d.addCallback(lambda _: threads.deferToThread(delete_test_env))
+        d.addErrback(lambda err: str(err))
         return d
 
     def test_reflector(self):