diff --git a/setup.py b/setup.py
index f9ab185..265f1cc 100644
--- a/setup.py
+++ b/setup.py
@@ -2,7 +2,7 @@
 
 from setuptools import setup
 
-install_requires = ['six']
+install_requires = ['six>=1.9.0']
 try:
     import xml.etree
 except ImportError: