1 files changed, 1 insertions, 1 deletions
diff --git a/setup.py b/setup.py
index 5f9ede8a..696fc824 100755
--- a/setup.py
+++ b/setup.py
@@ -57,7 +57,7 @@ CLASSIFIERS = filter(None, map(str.strip,
 INSTALL_REQUIRES = ['pyparsing >= 2.0.1', 'six']
 # unitest.mock was added in Python 3.3.  mock is a backport of unittest.mock to all versions of Python
 TESTS_REQUIRE = ['mock', 'pytest']
-DOCS_REQUIRE = ['sphinx', 'sphinx_rtd_theme', 'pyparsing']
+DOCS_REQUIRE = ['sphinx', 'sphinx_rtd_theme', 'pyparsing', 'six']
 
 setup(
     name="cmd2",