diff --git a/Gemfile b/Gemfile
index 74bc484..4701d2b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use Puma as the app server
-gem 'puma', '~> 3.11'
+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 80be064..6d8bd47 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -115,7 +115,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.2)
-    puma (3.11.4)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     racc (1.5.2)
     rack (2.2.3)
     rack-test (1.1.0)
@@ -238,7 +239,7 @@ DEPENDENCIES
   jbuilder (~> 2.5)
   listen (>= 3.0.5, < 3.2)
   pry
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2)
   rails-controller-testing
   rspec-rails (~> 3.7)