diff --git a/week3/sample_app/Gemfile b/week3/sample_app/Gemfile
index c7fdd65..6a6c2c6 100644
--- a/week3/sample_app/Gemfile
+++ b/week3/sample_app/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.0.7', '>= 5.0.7.2'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3', '~> 1.4.1'
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 3.12'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets
diff --git a/week3/sample_app/Gemfile.lock b/week3/sample_app/Gemfile.lock
index b8e6382..9008de8 100644
--- a/week3/sample_app/Gemfile.lock
+++ b/week3/sample_app/Gemfile.lock
@@ -111,7 +111,7 @@ GEM
     pry (0.12.2)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
-    puma (3.12.1)
+    puma (3.12.2)
     rack (2.0.7)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -218,7 +218,7 @@ DEPENDENCIES
   minitest (= 5.11.3)
   minitest-reporters (= 1.3.8)
   pg (~> 0.18)
-  puma (~> 3.0)
+  puma (~> 3.12)
   rails (~> 5.0.7, >= 5.0.7.2)
   rails-controller-testing (= 1.0.4)
   rails_12factor (= 0.0.2)