diff --git a/docs/conf.py b/docs/conf.py
index 6b19f967..8f174b64 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -4,7 +4,7 @@
 
 import os
 
-extensions = ['sphinx.ext.imgmath', 'sphinx.ext.viewcode']
+extensions = ['sphinx.ext.imgmath', 'sphinx.ext.viewcode', 'sphinx_rtd_theme']
 templates_path = ['_templates']
 source_suffix = '.rst'
 master_doc = 'index'
diff --git a/docs/requirements.txt b/docs/requirements.txt
index 4afd9bb6..f49e26d5 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -2,3 +2,4 @@ recommonmark
 Sphinx
 sphinx-autobuild
 sphinx-rtd-theme
+docutils==0.16