diff --git a/Gemfile b/Gemfile
index b319548..67a0f6f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ gem 'dotenv-rails', groups: [:development, :test]
 gem 'rails', '~> 5.2.3'
 gem 'pg'
 # 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 474c8bf..0fd117b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -123,7 +123,9 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (0.9.2)
-    mimemagic (0.3.3)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.1)
     mini_portile2 (2.4.0)
     minitest (5.13.0)
@@ -143,7 +145,8 @@ GEM
     pg (1.1.4)
     popper_js (1.14.5)
     public_suffix (3.0.3)
-    puma (3.12.4)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.2.2)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -263,7 +266,7 @@ DEPENDENCIES
   octicons_helper
   octokit (~> 4.0)
   pg
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   rails-i18n (~> 5.0)
   sass-rails (~> 5.0)