diff --git a/Gemfile b/Gemfile
index e8518b3..9d9664c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -10,7 +10,7 @@ end
 gem 'rails', '~> 5.1.7'
 gem 'mysql2'
 # Use Puma as the app server
-gem 'puma', '~> 3.12'
+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 43cef44..85d6d99 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -105,7 +105,8 @@ GEM
     nokogiri (1.10.5)
       mini_portile2 (~> 2.4.0)
     public_suffix (4.0.1)
-    puma (3.12.2)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -203,7 +204,7 @@ DEPENDENCIES
   jbuilder (~> 2.5)
   listen (>= 3.0.5, < 3.2)
   mysql2
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.1.7)
   sass-rails (~> 5.0)
   selenium-webdriver