diff --git a/Gemfile b/Gemfile
index eeb26c0..67d72d6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,7 +6,7 @@ ruby '2.4.1'
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.2.2'
 # Use Puma as the app server
-gem 'puma', '~> 3.12'
+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 d594718..81465b3 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -96,7 +96,9 @@ 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_mime (1.0.1)
     mini_portile2 (2.4.0)
     minitest (5.11.3)
@@ -106,7 +108,8 @@ GEM
       mini_portile2 (~> 2.4.0)
     pg (1.1.4)
     public_suffix (3.1.1)
-    puma (3.12.4)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -200,7 +203,7 @@ DEPENDENCIES
   jbuilder (~> 2.5)
   listen (>= 3.0.5, < 3.2)
   pg
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.2.2)
   sass-rails (~> 5.0)
   selenium-webdriver