diff --git a/Gemfile b/Gemfile
index d393340..73e1631 100644
--- a/Gemfile
+++ b/Gemfile
@@ -19,7 +19,7 @@ gem 'autoprefixer-rails', '~> 9.3.1'
 gem 'pry', '~> 0.12.2'
 gem 'rails', '~> 5.2.1'
 gem 'pg', '~> 0.21.0'
-gem 'puma', '~> 3.12.0'
+gem 'puma', '~> 4.3.12'
 gem 'sass-rails', '~> 5.0.7'
 gem 'uglifier', '~> 4.1.19'
 gem 'coffee-rails', '~> 4.2.2'
diff --git a/Gemfile.lock b/Gemfile.lock
index 1b1a292..d25de34 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -152,7 +152,9 @@ GEM
     mime-types (3.2.2)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2018.0812)
-    mimemagic (0.3.2)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_magick (4.9.4)
     mini_mime (1.0.1)
     mini_portile2 (2.4.0)
@@ -167,7 +169,8 @@ GEM
     pry (0.12.2)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
-    puma (3.12.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-pjax (1.0.0)
       nokogiri (~> 1.5)
@@ -286,7 +289,7 @@ DEPENDENCIES
   mini_magick (~> 4.9.4)
   pg (~> 0.21.0)
   pry (~> 0.12.2)
-  puma (~> 3.12.0)
+  puma (~> 4.3.12)
   rails (~> 5.2.1)
   rails-controller-testing (~> 1.0.2)
   rails_admin (~> 1.4.2)