diff --git a/acme/acme/client_test.py b/acme/acme/client_test.py
index d97b4920c..4bd762865 100644
--- a/acme/acme/client_test.py
+++ b/acme/acme/client_test.py
@@ -634,7 +634,7 @@ class ClientNetworkTest(unittest.TestCase):
 
         # Requests Library Exceptions
         except requests.exceptions.ConnectionError as z: #pragma: no cover
-            self.assertEqual("('Connection aborted.',"
+            self.assertEqual("('Connection aborted.', "
                              "error(111, 'Connection refused'))", str(z))
 
 class ClientNetworkWithMockedResponseTest(unittest.TestCase):