diff --git a/Gemfile b/Gemfile
index f741805..71665a1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ end
 
 gem 'rails', '~> 5.0.2'
 gem 'mysql2', '>= 0.3.18', '< 0.5'
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 gem 'go-on-rails', '~> 0.4.0'
 
 group :development, :test do
diff --git a/Gemfile.lock b/Gemfile.lock
index 874c693..2718f49 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -69,7 +69,8 @@ GEM
     nio4r (2.5.2)
     nokogiri (1.10.7)
       mini_portile2 (~> 2.4.0)
-    puma (3.12.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -128,7 +129,7 @@ DEPENDENCIES
   go-on-rails (~> 0.4.0)
   listen (~> 3.0.5)
   mysql2 (>= 0.3.18, < 0.5)
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.0.2)
   spring
   spring-watcher-listen (~> 2.0.0)