diff --git a/rails/Gemfile b/rails/Gemfile
index e801831..3122e2f 100644
--- a/rails/Gemfile
+++ b/rails/Gemfile
@@ -10,7 +10,7 @@ gem 'rails', '~> 5.1.4'
 # Use mysql as the database for Active Record
 gem 'mysql2', '>= 0.3.18', '< 0.5'
 # 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 ca8d473..e753ada 100644
--- a/rails/Gemfile.lock
+++ b/rails/Gemfile.lock
@@ -332,7 +332,8 @@ GEM
     posix-spawn (0.3.13)
     powerpack (0.1.2)
     public_suffix (3.0.2)
-    puma (3.12.0)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     rack (2.0.5)
     rack-cors (1.0.2)
     rack-protection (2.0.3)
@@ -509,7 +510,7 @@ DEPENDENCIES
   omniauth (>= 1.7.0)
   paranoia (~> 2.3.1)
   posix-spawn (~> 0.3.13)
-  puma (~> 3.7)
+  puma (~> 4.3)
   rack-cors
   rails (~> 5.1.4)
   rails-i18n