diff --git a/deluge/ui/web/auth.py b/deluge/ui/web/auth.py
index 7f6df52fc..94ba6decd 100644
--- a/deluge/ui/web/auth.py
+++ b/deluge/ui/web/auth.py
@@ -13,6 +13,7 @@ import random
 import time
 from datetime import datetime, timedelta
 from email.utils import formatdate
+from functools import reduce
 
 from twisted.internet.task import LoopingCall