diff --git a/Gemfile b/Gemfile
index 5c651f3..e91c625 100644
--- a/Gemfile
+++ b/Gemfile
@@ -12,7 +12,7 @@ gem 'rails', '~> 5.1.3'
 gem 'pg', '~> 0.18'
 
 # Use Puma as the app server
-gem 'puma', '~> 3.7'
+gem 'puma', '~> 3.12', '>= 3.12.6'
 
 # Use jQuery as default JS library
 gem 'jquery-rails'