diff --git a/Gemfile b/Gemfile
index 6e02e5c..2257729 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,6 +2,7 @@ source "https://rubygems.org"
 
 gem 'sinatra'
 gem 'dnsruby'
+gem 'rack'
 group :test do
   gem 'minitest'
   gem 'mina'
diff --git a/Gemfile.lock b/Gemfile.lock
index 391ae0c..37a49cf 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -30,6 +30,7 @@ DEPENDENCIES
   dnsruby
   mina
   minitest
+  rack
   sinatra
   thin