diff --git a/requirements.txt b/requirements.txt
index 72b13e63ba..3376fc1a1d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -46,4 +46,5 @@ django-sekizai<0.7
 django-mptt>=0.5.3
 sorl-thumbnail
 networkx
+pygraphviz
 -r repo-requirements.txt