diff --git a/requirements.txt b/requirements.txt
index 06f022e2..be232768 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,7 +4,7 @@
 
 pbr>=0.6,!=0.7,<1.0
 Babel>=1.3
-six>=1.7.0
+six>=1.9.0
 iso8601>=0.1.9
 oslo.i18n>=1.3.0  # Apache-2.0
 netaddr>=0.7.12