diff --git a/examples/rails5_app/Gemfile b/examples/rails5_app/Gemfile
index 260a76a..5c75588 100644
--- a/examples/rails5_app/Gemfile
+++ b/examples/rails5_app/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.0.2'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets
diff --git a/examples/rails5_app/Gemfile.lock b/examples/rails5_app/Gemfile.lock
index 2364fd2..f80956a 100644
--- a/examples/rails5_app/Gemfile.lock
+++ b/examples/rails5_app/Gemfile.lock
@@ -88,7 +88,8 @@ GEM
     nokogiri (1.10.5)
       mini_portile2 (~> 2.4.0)
     orm_adapter (0.5.0)
-    puma (3.7.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -174,7 +175,7 @@ DEPENDENCIES
   jbuilder (~> 2.5)
   jquery-rails
   listen (~> 3.0.5)
-  puma (~> 3.0)
+  puma (~> 4.3)
   rails (~> 5.0.2)
   sass-rails (~> 5.0)
   spring