diff --git a/Gemfile b/Gemfile
index 0400404..fb24497 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,7 +7,7 @@ gem 'dotenv-rails', '~> 0.10.0'
 gem 'rails', '~> 3.2.22'
 gem 'mysql2', '~> 0.3.17'
 gem 'dalli', '~> 2.7.0'
-gem 'puma', '~> 2.11.1'
+gem 'puma', '~> 4.3.12'
 
 gem 'i18n-js'
 gem 'exceptional', '~> 2.0.33'
diff --git a/Gemfile.lock b/Gemfile.lock
index 1c6cc29..52076cb 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -188,6 +188,7 @@ GEM
       net-ssh (>= 2.6.5)
     net-ssh (4.2.0)
     newrelic_rpm (3.13.0.299)
+    nio4r (2.3.1)
     nokogiri (1.9.1)
       mini_portile2 (~> 2.4.0)
     oj (2.5.5)
@@ -206,8 +207,8 @@ GEM
       byebug (~> 2.7)
       pry (~> 0.10)
     public_suffix (3.0.1)
-    puma (2.11.3)
-      rack (>= 1.1, < 2.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     quiet_assets (1.0.3)
       railties (>= 3.1, < 5.0)
     rack (1.4.7)
@@ -356,7 +357,7 @@ DEPENDENCIES
   oj (~> 2.5.5)
   poltergeist (~> 1.6.0)
   pry-byebug (~> 1.3.2)
-  puma (~> 2.11.1)
+  puma (~> 4.3.12)
   quiet_assets (~> 1.0.2)
   rails (~> 3.2.22)
   rails_autolink (~> 1.1.5)