diff --git a/requirements.txt b/requirements.txt
index 545d892c..3e7a757f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,6 +12,6 @@ oslo.utils>=1.2.0                       # Apache-2.0
 SQLAlchemy>=0.9.7,<=0.9.99
 sqlalchemy-migrate>=0.9.1,!=0.9.2
 stevedore>=1.1.0  # Apache-2.0
-six>=1.7.0
+six>=1.9.0
 testresources>=0.2.4
 testscenarios>=0.4