diff --git a/setup.py b/setup.py
index 7f3e4a3..e01b59e 100644
--- a/setup.py
+++ b/setup.py
@@ -44,6 +44,7 @@
         'Django>=1.8.11',
         'djangorestframework>=3.3.3',
         'voluptuous>=0.8.10',
+        'six>=1.17.0',
     ],
     classifiers=[
         'Development Status :: 3 - Alpha',