diff --git a/Gemfile b/Gemfile
index ad212d7..82342ab 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ end
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.2'
 # Use Puma as the app server
-gem 'puma', '~> 3.6.2'
+gem 'puma', '~> 4.3.12'
 # Use Uglifier as compressor for JavaScript assets
 gem 'uglifier', '>= 1.3.0'
 # See https://github.com/rails/execjs#readme for more supported runtimes
diff --git a/Gemfile.lock b/Gemfile.lock
index 3329d79..7da73d4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -127,7 +127,9 @@ GEM
       mimemagic (~> 0.3.2)
     memcachier (0.0.2)
     method_source (0.9.1)
-    mimemagic (0.3.2)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.1)
     mini_portile2 (2.3.0)
     minitest (5.11.3)
@@ -152,7 +154,8 @@ GEM
     pry-rails (0.3.7)
       pry (>= 0.10.4)
     public_suffix (3.0.3)
-    puma (3.6.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-proxy (0.6.5)
       rack
@@ -259,7 +262,7 @@ DEPENDENCIES
   mongoid (~> 7.0.2)
   nokogiri (~> 1.8.0)
   pry-rails (~> 0.3.6)
-  puma (~> 3.6.2)
+  puma (~> 4.3.12)
   rails (~> 5.2)
   rubocop (~> 0.49)
   selenium-webdriver