diff --git a/Gemfile b/Gemfile
index a9462ad..d7eebb9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ end
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.1.6'
 # 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 17dd2f0..c65eeb2 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -139,7 +139,8 @@ GEM
     pg (1.1.4)
     pg (1.1.4-x86-mingw32)
     public_suffix (3.0.3)
-    puma (3.12.6)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     racc (1.5.2)
     rack (2.2.3)
     rack-test (1.1.0)
@@ -241,7 +242,7 @@ DEPENDENCIES
   kaminari
   listen (>= 3.0.5, < 3.2)
   pg
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.1.6)
   redis
   sass-rails (~> 5.0)