diff --git a/setup.py b/setup.py
index 2fb77ae..401236e 100644
--- a/setup.py
+++ b/setup.py
@@ -38,7 +38,7 @@
     url = URL,
     packages = find_packages(exclude=['*tests']), #FIXME validate this
     entry_point = { 'console_scripts': console_scripts },
-    install_requires = ['pyparsing', 'pyyaml'],   #FIXME pygit2 (require libffi-dev, libgit2-dev 0.26.x )
+    install_requires = ['pyparsing', 'pyyaml', 'six'], #FIXME pygit2 (require libffi-dev, libgit2-dev 0.26.x )
 
     classifiers=[
         'Development Status :: 4 - Beta',