diff --git a/circle.yml b/circle.yml
index efd2bdd..c685594 100644
--- a/circle.yml
+++ b/circle.yml
@@ -1,6 +1,8 @@
 machine:
   python:
     version: 2.7.3
+  ruby:
+    version: 2.3.5
   services:
     - docker