diff --git a/Gemfile b/Gemfile
index 8d693ca8..f2277d37 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ end
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.0.2'
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+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 755c077b..295dea5f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -142,7 +142,9 @@ GEM
     mime-types (3.1)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2016.0521)
-    mimemagic (0.3.2)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_portile2 (2.1.0)
     minitest (5.10.1)
     multi_json (1.12.1)
@@ -192,7 +194,8 @@ GEM
       attr_required (>= 0.0.5)
       rest-client
     pg (0.20.0)
-    puma (3.8.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.3)
     rack-protection (2.0.0)
       rack
@@ -326,7 +329,7 @@ DEPENDENCIES
   paperclip
   paypal-express
   pg
-  puma (~> 3.0)
+  puma (~> 4.3)
   rails (~> 5.0.2)
   recaptcha
   redis (~> 3.0)