diff --git a/acme/acme/client_test.py b/acme/acme/client_test.py
index 813898d20..6509f951b 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.', error(111, 'Connection Refused'))", str(z))
+            self.assertEqual("('Connection aborted.', error(111, 'Connection refused'))", str(z))
 
 class ClientNetworkWithMockedResponseTest(unittest.TestCase):
     """Tests for acme.client.ClientNetwork which mock out response."""