diff --git a/requirements.txt b/requirements.txt
index 3b9ec44..4dea533 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -19,6 +19,6 @@
 testrepository>=0.0.17
 oslo.config>=1.2.0
 eventlet>=0.13.0
-six<1.4.0
+six>=1.4.1
 iso8601>=0.1.4
 fixtures>=0.3.14