diff --git a/Gemfile b/Gemfile
index 046401e..36a05c7 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.2'
 # Use mysql as the database for Active Record
 gem 'mysql2', '>= 0.4.4', '< 0.6.0'
 # 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 016e2a7..738378c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -93,7 +93,9 @@ GEM
     materialize-sass (1.0.0)
       autoprefixer-rails (>= 6.0.3)
     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 (5.11.3)
@@ -103,7 +105,8 @@ GEM
     nio4r (2.3.1)
     nokogiri (1.10.3)
       mini_portile2 (~> 2.4.0)
-    puma (3.12.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-proxy (0.6.5)
       rack
@@ -195,7 +198,7 @@ DEPENDENCIES
   material_icons
   materialize-sass
   mysql2 (>= 0.4.4, < 0.6.0)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.2)
   sass-rails (~> 5.0)
   spring