diff --git a/Gemfile b/Gemfile
index 86af671..b91c68f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ end
 
 gem 'rails', '~> 5.0.1'
 gem 'pg', '~> 0.18'
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 gem 'sass-rails', '~> 5.0'
 gem 'uglifier', '>= 1.3.0'
 gem 'coffee-rails', '~> 4.2'
diff --git a/Gemfile.lock b/Gemfile.lock
index 618147f..7b5b427 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -166,7 +166,8 @@ GEM
       coderay (~> 1.1)
       method_source (~> 1.0)
     public_suffix (4.0.6)
-    puma (3.12.6)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     racc (1.5.2)
     rack (2.2.3)
     rack-test (0.6.3)
@@ -284,7 +285,7 @@ DEPENDENCIES
   paranoia (~> 2.2)
   pg (~> 0.18)
   pry
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.0.1)
   rspec-rails
   sass-rails (~> 5.0)