diff --git a/Gemfile b/Gemfile
index bbc57c9..1f91779 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.3'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3', '~> 1.3.6'
 # 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 41318dc..5e2c155 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -152,7 +152,9 @@ 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)
     mini_racer (0.2.4)
@@ -198,7 +200,8 @@ GEM
       equatable (~> 0.5.0)
       tty-color (~> 0.4.0)
     public_suffix (3.0.3)
-    puma (3.12.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-proxy (0.6.5)
       rack
@@ -338,7 +341,7 @@ DEPENDENCIES
   foreman
   jbuilder (~> 2.5)
   listen (>= 3.0.5, < 3.2)
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   rails-hyperstack (~> 1.0.alpha)
   sass-rails (~> 5.0)