diff --git a/Gemfile b/Gemfile
index e5df5f0..4f6026c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,4 +1,5 @@
 source 'https://rubygems.org'
+ruby '2.1.3'
 
 gem 'sinatra'
 gem 'sinatra-contrib'