diff --git a/Gemfile b/Gemfile
index 357151d..b954135 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ require 'net/http'
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.1.6'
 # Use Puma as the app server
-gem 'puma', '3.12.2'
+gem 'puma', '4.3.11'
 # Use SCSS for stylesheets
 gem 'sass-rails', '5.0.6'
 # Use Uglifier as compressor for JavaScript assets
diff --git a/Gemfile.lock b/Gemfile.lock
index f35bbc5..183fdba 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -100,7 +100,8 @@ GEM
       ast (~> 2.4.0)
     pg (0.20.0)
     public_suffix (4.0.1)
-    puma (3.12.2)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-proxy (0.6.5)
       rack
@@ -238,7 +239,7 @@ DEPENDENCIES
   listen (= 3.1.5)
   materialize-sass
   pg (= 0.20.0)
-  puma (= 3.12.2)
+  puma (= 4.3.11)
   rails (~> 5.1.6)
   rspec-rails (~> 3.5)
   rswag