diff --git a/tools/pip-requires b/tools/pip-requires
index afcd4229eb..5d57cf0418 100644
--- a/tools/pip-requires
+++ b/tools/pip-requires
@@ -54,6 +54,7 @@ routes>=1.12.3
 rtslib>=2.1.fb27
 setuptools_git>=0.4
 simplejson>=2.0.9
+six
 sqlalchemy>=0.7,<=0.7.99
 sqlalchemy-migrate>=0.7
 stevedore>=0.7