diff --git a/Gemfile b/Gemfile
index 83c4e59..ecc83b9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.1.3'
 # Use postgresql as the database for Active Record
 gem 'pg', '~> 0.18'
 # 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/Gemfile.lock b/Gemfile.lock
index bec5be9..6adb17f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -114,7 +114,8 @@ GEM
       mini_portile2 (~> 2.2.0)
     pg (0.21.0)
     public_suffix (3.0.0)
-    puma (3.10.0)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     rack (2.0.3)
     rack-attack (5.0.1)
       rack
@@ -212,7 +213,7 @@ DEPENDENCIES
   jquery-rails
   listen (>= 3.0.5, < 3.2)
   pg (~> 0.18)
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.1.3)
   sass-rails (~> 5.0)
   selenium-webdriver