diff --git a/Gemfile b/Gemfile
index 94cb2de..f44f463 100644
--- a/Gemfile
+++ b/Gemfile
@@ -70,4 +70,6 @@ group :production do
   gem 'pg','0.17.1'
   gem 'rails_12factor','0.0.2'
   gem 'puma', '2.11.1'
-end
\ No newline at end of file
+end
+
+ruby '2.1.5'
\ No newline at end of file