diff --git a/setup.py b/setup.py
index c0cf15354..0ec655730 100755
--- a/setup.py
+++ b/setup.py
@@ -86,6 +86,7 @@ setup(
     },
 
     install_requires=[
+        'six',
         'enum34>=1.0.4',
         'mutagen>=1.27',
         'munkres',
diff --git a/tox.ini b/tox.ini
index 22d4aba2a..fe05a52fa 100644
--- a/tox.ini
+++ b/tox.ini
@@ -24,6 +24,7 @@ deps =
     jellyfish
     python-mpd2
     coverage
+    six
 
 [_flake8]
 deps =