diff --git a/hello-rails/Gemfile b/hello-rails/Gemfile
index 85634cf..a3a23bf 100644
--- a/hello-rails/Gemfile
+++ b/hello-rails/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.1.6'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use Puma as the app server
-gem 'puma', '~> 3.7'
+gem 'puma', '~> 3.12'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets
diff --git a/hello-rails/Gemfile.lock b/hello-rails/Gemfile.lock
index c341a11..f8547e7 100644
--- a/hello-rails/Gemfile.lock
+++ b/hello-rails/Gemfile.lock
@@ -88,7 +88,7 @@ GEM
     nokogiri (1.10.4)
       mini_portile2 (~> 2.4.0)
     public_suffix (4.0.1)
-    puma (3.12.1)
+    puma (3.12.2)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -177,7 +177,7 @@ DEPENDENCIES
   coffee-rails (~> 4.2)
   jbuilder (~> 2.5)
   listen (>= 3.0.5, < 3.2)
-  puma (~> 3.7)
+  puma (~> 3.12)
   rails (~> 5.1.6)
   sass-rails (~> 5.0)
   selenium-webdriver