diff --git a/.travis.yml b/.travis.yml
index ca0673e15..c732876ef 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,6 +2,11 @@ language: python
 sudo: false
 cache: pip
 
+addons:
+  apt:
+    packages:
+      - graphviz
+
 python:
   - "3.5"
   - "3.4"