diff --git a/docs/requirements.txt b/docs/requirements.txt
index 3ffbffed..9e6b6214 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,3 +1,4 @@
 Sphinx==1.3.5
 sphinxcontrib-napoleon==0.4.4
+sphinx-rtd-theme>=0.1.9
 recommonmark