diff --git a/Gemfile b/Gemfile
index d828d97..2e42a3d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -14,7 +14,7 @@ gem 'octokit',                      '~> 3.7.0'
 gem 'octicons-rails',               '~> 2.1.1'
 gem 'actionpack-action_caching',    '~> 1.1.1'
 gem 'redis',                        '~> 3.2.0'
-gem 'puma',                         '~> 2.11.1'
+gem 'puma',                         '~> 4.3.12'
 gem 'httparty',                     '~> 0.13.3'
 gem 'kaminari',                     '~> 0.16.3'
 gem 'dalli',                        '~> 2.7.4'
diff --git a/Gemfile.lock b/Gemfile.lock
index ed25eb3..ae0a5ff 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -138,6 +138,7 @@ GEM
       net-ssh (>= 2.6.5)
     net-ssh (4.2.0)
     newrelic_rpm (3.9.9.275)
+    nio4r (2.5.2)
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
     oauth2 (1.4.0)
@@ -166,11 +167,11 @@ GEM
     pry-byebug (3.5.1)
       byebug (~> 9.1)
       pry (~> 0.10)
-    puma (2.11.3)
-      rack (>= 1.1, < 2.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     quiet_assets (1.1.0)
       railties (>= 3.1, < 5.0)
-    rack (1.6.8)
+    rack (1.6.13)
     rack-test (0.6.3)
       rack (>= 1.0)
     rails (4.2.7.1)
@@ -309,7 +310,7 @@ DEPENDENCIES
   omniauth-github (~> 1.1.2)
   pg (~> 0.18.2)
   pry-byebug (~> 3.1)
-  puma (~> 2.11.1)
+  puma (~> 4.3.12)
   quiet_assets (~> 1.1.0)
   rails (~> 4.2.7.1)
   redis (~> 3.2.0)