diff --git a/Gemfile b/Gemfile
index aca39a6b..b63386b9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,6 @@
 source 'https://rubygems.org'
 
-gem 'sinatra', '~> 1.0'
+gem 'sinatra', '~> 4.0', '>= 4.0.0'
 gem 'shotgun', :group => :reloadable
 gem 'thin', :group => :reloadable
 gem 'rake'