diff --git a/Gemfile b/Gemfile
index 416f395..e38095b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.3'
 gem 'pg'
 gem 'mysql2'
 # 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 8332825..707ca6c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -120,7 +120,8 @@ GEM
       terrapin (~> 0.6.0)
     pg (1.1.4)
     public_suffix (4.0.1)
-    puma (3.12.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -242,7 +243,7 @@ DEPENDENCIES
   mysql2
   paperclip (~> 6.0.0)
   pg
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   redis-rails
   sass-rails (~> 5.0)