diff --git a/Gemfile b/Gemfile
index 57056ed..c9c55ca 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,5 +1,7 @@
 source 'http://rubygems.org'
 
+ruby '2.3.3'
+
 gemspec
 
 gem 'rails', '~> 4.2.8'