diff --git a/letsencrypt/client/tests/challenge_util_test.py b/letsencrypt/client/tests/challenge_util_test.py
index 33358410a..8bad21341 100644
--- a/letsencrypt/client/tests/challenge_util_test.py
+++ b/letsencrypt/client/tests/challenge_util_test.py
@@ -1,11 +1,12 @@
 """Tests for challenge_util."""
-import M2Crypto
-import mock
 import os
 import pkg_resources
 import re
 import unittest
 
+import M2Crypto
+import mock
+
 from letsencrypt.client import challenge_util
 from letsencrypt.client import client
 from letsencrypt.client import CONFIG