diff --git a/offlineimap/imapserver.py b/offlineimap/imapserver.py
index 28511bb..6534f13 100644
--- a/offlineimap/imapserver.py
+++ b/offlineimap/imapserver.py
@@ -24,6 +24,7 @@ import offlineimap.accounts
 import hmac
 import socket
 import base64
+import errno
 
 from socket import gaierror
 try: