diff --git a/rails/Gemfile b/rails/Gemfile
index 515f954..ac3b925 100644
--- a/rails/Gemfile
+++ b/rails/Gemfile
@@ -9,7 +9,7 @@ end
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.1.3'
 # Use Puma as the app server
-gem 'puma', '~> 3.7'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets
diff --git a/rails/Gemfile.lock b/rails/Gemfile.lock
index 6ce9722..487a319 100644
--- a/rails/Gemfile.lock
+++ b/rails/Gemfile.lock
@@ -164,7 +164,8 @@ GEM
     polyamorous (1.3.3)
       activerecord (>= 3.0)
     public_suffix (3.0.2)
-    puma (3.11.3)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.5)
     rack-pjax (1.0.0)
       nokogiri (~> 1.5)
@@ -321,7 +322,7 @@ DEPENDENCIES
   mini_racer
   paranoia
   pg
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.1.3)
   rails_admin
   rails_db