diff --git a/Gemfile b/Gemfile
index 8845ac4..9c005f6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.2.3'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use Puma as the app server
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 4.3', '>= 4.3.9'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
 # gem 'jbuilder', '~> 2.5'
 # Use Redis adapter to run Action Cable in production