diff --git a/requirements.txt b/requirements.txt
index 7b06735a4f..c8c4ef7896 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -26,7 +26,7 @@ jsonschema>=2.0.0,<3.0.0
 python-cinderclient>=1.1.0
 python-neutronclient>=2.3.6,<3
 python-glanceclient>=0.15.0
-six>=1.7.0
+six>=1.9.0
 stevedore>=1.1.0  # Apache-2.0
 websockify>=0.6.0,<0.7
 oslo.concurrency>=1.4.1         # Apache-2.0