diff --git a/Gemfile b/Gemfile
index 87e376b..b89f644 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,4 +2,4 @@ source 'https://rubygems.org'
 
 ruby '2.4.5'
 
-gem 'rack'
+gem 'rack', '>= 2.2.14'