diff --git a/Gemfile b/Gemfile
index 9dca597..2df657e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.4', '>= 5.2.4.1'
 # Use postgresql as the database for Active Record
 gem 'pg'
 # 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 7e8cc18..13a3e0a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -120,7 +120,8 @@ GEM
       mini_portile2 (~> 2.4.0)
     pg (1.2.3)
     public_suffix (4.0.5)
-    puma (3.12.6)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     rack (2.2.3)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -239,7 +240,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   mini_magick (~> 4.5, >= 4.5.1)
   pg
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.4, >= 5.2.4.1)
   rspec-rails
   sass-rails (~> 5.0)