diff --git a/Gemfile b/Gemfile
index d4f91b6..2651591 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.2'
 # Use postgresql as the database for Active Record
 gem 'pg', '>= 0.18', '< 2.0'
 # 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 112bb89..5c3623a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -160,7 +160,8 @@ GEM
     os (1.0.0)
     pg (1.1.4)
     public_suffix (3.0.3)
-    puma (3.12.2)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-cors (1.0.5)
       rack (>= 1.6.0)
@@ -264,7 +265,7 @@ DEPENDENCIES
   knock
   listen (>= 3.0.5, < 3.2)
   pg (>= 0.18, < 2.0)
-  puma (~> 3.12)
+  puma (~> 4.3)
   rack-cors
   rails (~> 5.2.2)
   rubyzip (>= 1.0.0)