diff --git a/setup.py b/setup.py
index 79e3f20..e276339 100755
--- a/setup.py
+++ b/setup.py
@@ -51,7 +51,8 @@ setup(name='talon',
           "scikit-learn==0.16.1", # pickled versions of classifier, else rebuild
           'chardet>=1.0.1',
           'cchardet>=0.3.5',
-          'cssselect'
+          'cssselect',
+          'six>=1.10.0',
           ],
       tests_require=[
           "mock",