diff --git a/dev-requirements.txt b/dev-requirements.txt
index c70694c1e..08bfc7d50 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -27,6 +27,7 @@ freezegun==0.3.6
 guppy==0.1.10
 snakefood==1.4
 Sphinx==1.4.6
+sphinx_rtd_theme
 
 # Requirements for OIDC provider
 pyaml==15.03.1