diff --git a/Gemfile b/Gemfile
index 1a14045..e30b934 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.1'
 # Use postgres 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 671f11f..d9a5d81 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -144,7 +144,9 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (1.0.0)
-    mimemagic (0.3.5)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.2)
     mini_portile2 (2.5.0)
     minitest (5.14.4)
@@ -184,7 +186,8 @@ GEM
       coderay (~> 1.1)
       method_source (~> 1.0)
     public_suffix (4.0.6)
-    puma (3.12.6)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     racc (1.5.2)
     rack (2.2.3)
     rack-proxy (0.6.5)
@@ -329,7 +332,7 @@ DEPENDENCIES
   opal-rails
   pg
   pry
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.1)
   rubocop
   sass-rails (~> 5.0)