diff --git a/Gemfile b/Gemfile
index f9452d7..2623bcd 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,7 +4,7 @@ source "https://rubygems.org"
 
 git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
 
-gem "sinatra"
+gem "sinatra", ">= 4.1.0"
 gem "twilio-ruby"
 gem "mime-types"
 gem "rack-test"