diff --git a/Gemfile b/Gemfile
index 21b3eb2..716b1bc 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.0.7'
 # Use postgresql as the database for Active Record
 
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+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 f9273f8..dc28e22 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -80,7 +80,8 @@ GEM
     nio4r (2.5.2)
     nokogiri (1.10.9)
       mini_portile2 (~> 2.4.0)
-    puma (3.12.6)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.2.2)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -162,7 +163,7 @@ DEPENDENCIES
   jquery-rails
   listen (~> 3.0.5)
   mysql2
-  puma (~> 3.0)
+  puma (~> 4.3)
   rails (~> 5.0.7)
   rake (~> 12.3.2)
   sass-rails (~> 5.0)