diff --git a/requirements.txt b/requirements.txt
index 5bef251..79a76f0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,4 +4,4 @@
 
 pbr>=0.6,!=0.7,<1.0
 Babel>=1.3
-six>=1.7.0
+six>=1.9.0