diff --git a/Gemfile b/Gemfile
index fdaae31..2440840 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ gem 'pg', '>= 0.18', '< 2.0'
 gem 'aws-sdk-s3', require: false
 
 # 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 bc1b014..6317ff8 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -165,7 +165,9 @@ GEM
     marcel (0.3.2)
       mimemagic (~> 0.3.2)
     method_source (0.9.0)
-    mimemagic (0.3.2)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.0)
     mini_portile2 (2.3.0)
     minitest (5.11.3)
@@ -179,7 +181,8 @@ GEM
     pg (1.0.0)
     popper_js (1.12.9)
     public_suffix (3.0.2)
-    puma (3.11.4)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.4)
     rack-test (1.0.0)
       rack (>= 1.0, < 3)
@@ -316,7 +319,7 @@ DEPENDENCIES
   jquery-rails
   listen (>= 3.0.5, < 3.2)
   pg (>= 0.18, < 2.0)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.0)
   rails-controller-testing
   rails-erd