diff --git a/Gemfile b/Gemfile
index 1787f4f..19c237d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.0'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # 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 019ab5f..6b418c2 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -130,7 +130,9 @@ 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 (1.0.2)
     mini_portile2 (2.4.0)
     mini_racer (0.2.6)
@@ -147,7 +149,8 @@ GEM
       rack (>= 1.6.2, < 3)
     orm_adapter (0.5.0)
     public_suffix (4.0.1)
-    puma (3.12.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-pjax (1.1.0)
       nokogiri (~> 1.5)
@@ -269,7 +272,7 @@ DEPENDENCIES
   mini_racer
   mysql2
   omniauth
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.2.0)
   rails_admin
   selenium-webdriver