diff --git a/.travis.yml b/.travis.yml
index 4b5ed106..489248d5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,6 +12,7 @@ addons:
   apt:
     packages:
       - expect-dev # provides unbuffer utility
+      - graphviz
 
 stages:
   - linting