diff --git a/Gemfile b/Gemfile
index a0bae53..501b240 100644
--- a/Gemfile
+++ b/Gemfile
@@ -10,7 +10,7 @@ gem 'rails', '~> 5.2.1'
 # 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'
 
 # Rack middleware for blocking & throttling
 gem 'rack-attack'
diff --git a/Gemfile.lock b/Gemfile.lock
index efcb7fe..aac667a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -110,7 +110,9 @@ 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_magick (4.9.5)
     mini_mime (1.0.2)
     mini_portile2 (2.4.0)
@@ -127,7 +129,8 @@ GEM
     parser (2.6.5.0)
       ast (~> 2.4.0)
     public_suffix (4.0.1)
-    puma (3.12.1)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     pundit (2.1.0)
       activesupport (>= 3.0.0)
     rack (2.0.7)
@@ -249,7 +252,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   mini_magick (~> 4.8)
   mysql2 (>= 0.4.4, < 0.6.0)
-  puma (~> 3.11)
+  puma (~> 4.3)
   pundit
   rack-attack
   rack-cors