diff --git a/extend-rails/Gemfile b/extend-rails/Gemfile
index 8af0a68..410710f 100644
--- a/extend-rails/Gemfile
+++ b/extend-rails/Gemfile
@@ -25,7 +25,7 @@ gem 'redis'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use Puma as the app server
-gem 'puma', '~> 3.7'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets
diff --git a/extend-rails/Gemfile.lock b/extend-rails/Gemfile.lock
index 87881c7..f5299e9 100644
--- a/extend-rails/Gemfile.lock
+++ b/extend-rails/Gemfile.lock
@@ -134,7 +134,8 @@ GEM
     pry-rails (0.3.9)
       pry (>= 0.10.4)
     public_suffix (3.0.3)
-    puma (3.12.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-proxy (0.6.5)
       rack
@@ -248,7 +249,7 @@ DEPENDENCIES
   pry
   pry-byebug
   pry-rails
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.1.4)
   rb-readline
   redis