diff --git a/Gemfile b/Gemfile
index f6aeb04..a015bcc 100644
--- a/Gemfile
+++ b/Gemfile
@@ -10,7 +10,7 @@ gem 'rails', '~> 5.2.2', '>= 5.2.2.1'
 # Use postgresql as the database for Active Record
 gem 'pg', '>= 0.18', '< 2.0'
 # 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 e0e2146..001b9e1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -135,7 +135,9 @@ GEM
     mime-types (3.2.2)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2019.0331)
-    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)
@@ -158,7 +160,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.3)
-    puma (3.12.1)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -290,7 +293,7 @@ DEPENDENCIES
   mechanize
   parallel
   pg (>= 0.18, < 2.0)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.2, >= 5.2.2.1)
   rspec-rails (~> 3.8)
   sass-rails (~> 5.0)