diff --git a/requirements.txt b/requirements.txt
index 6a3edec5b..e1346abb8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -21,7 +21,7 @@ python-ceilometerclient>=1.0.2
 python-swiftclient>=1.2
 lxml>=2.3
 requests>=1.1
-six
+six<1.4.0
 WSME>=0.5b2
 PyYAML>=3.1.0
 -f http://tarballs.openstack.org/oslo.config/oslo.config-1.2.0a3.tar.gz#egg=oslo.config-1.2.0a3