diff --git a/.travis.yml b/.travis.yml
index 863df92..9168c91 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,6 @@
 language: ruby
 rvm:
-- 2.3.3
+- 2.4
 # branch whitelist, only for GitHub Pages
 branches:
   only: