diff --git a/kata-1-procs-and-blocks/Gemfile b/kata-1-procs-and-blocks/Gemfile
index 61fc4b3..1014c24 100644
--- a/kata-1-procs-and-blocks/Gemfile
+++ b/kata-1-procs-and-blocks/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.3'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use Puma as the app server
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets
diff --git a/kata-1-procs-and-blocks/Gemfile.lock b/kata-1-procs-and-blocks/Gemfile.lock
index 5030d98..63609aa 100644
--- a/kata-1-procs-and-blocks/Gemfile.lock
+++ b/kata-1-procs-and-blocks/Gemfile.lock
@@ -114,7 +114,8 @@ GEM
     pry-rails (0.3.9)
       pry (>= 0.10.4)
     public_suffix (3.1.1)
-    puma (3.12.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -210,7 +211,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   pry-byebug
   pry-rails
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   rb-readline
   sass-rails (~> 5.0)