diff --git a/setup.py b/setup.py
index 1455bda..f67b636 100644
--- a/setup.py
+++ b/setup.py
@@ -34,5 +34,6 @@ def readme():
                         "scikit-learn",
                         "scipy"],
       extras_require={'docs': ["sphinx-pypi-upload",
+                               "numpydoc",
                                "Sphinx"]},
       scripts=['aimfast/bin/aimfast'])