diff --git a/requirements.txt b/requirements.txt
index 5c6a983..d24b3d1 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,5 +6,5 @@ jsonschema>=2.0.0,<3.0.0
 pbr>=0.6,!=0.7,<1.0
 python-keystoneclient>=1.1.0
 requests>=2.2.0,!=2.4.0
-six>=1.7.0
+six>=1.9.0
 stevedore>=1.1.0  # Apache-2.0