diff --git a/Gemfile b/Gemfile
index 8204c28..7930300 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,7 +7,7 @@ end
 
 gem 'rails', '~> 5.0.2'
 gem 'pg', '~> 0.18'
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 4.3'
 gem 'simplecov', :require => false, :group => :test
 
 group :development, :test do
diff --git a/Gemfile.lock b/Gemfile.lock
index 392a895..6e0ac31 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -83,7 +83,8 @@ GEM
     nokogiri (1.8.3)
       mini_portile2 (~> 2.3.0)
     pg (0.21.0)
-    puma (3.11.4)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.5)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -169,7 +170,7 @@ DEPENDENCIES
   factory_girl_rails
   listen (~> 3.0.5)
   pg (~> 0.18)
-  puma (~> 3.0)
+  puma (~> 4.3)
   rails (~> 5.0.2)
   rspec-rails
   shoulda-matchers