diff --git a/requirements.txt b/requirements.txt
index a3b3d66e..cac75167 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,6 +12,7 @@ Babel>=1.3
 six>=1.9.0
 iso8601>=0.1.9
 oslo.i18n>=1.5.0  # Apache-2.0
+pytz>=2013.6
 netaddr>=0.7.12
 netifaces>=0.10.4
 debtcollector>=0.3.0  # Apache-2.0