diff --git a/requirements.txt b/requirements.txt
index 3a7d63e..f81903b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,5 +6,5 @@ bunch >=1.0.0
 gevent ==0.13.6
 isodate >=0.4.4
 requests ==0.14.0
-pytz
+pytz >=2011k
 ordereddict