diff --git a/lessonThree/app/Gemfile b/lessonThree/app/Gemfile
index 4fdc50a..7f840b1 100644
--- a/lessonThree/app/Gemfile
+++ b/lessonThree/app/Gemfile
@@ -24,7 +24,7 @@ gem 'rails-ujs', '~> 0.1.0'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3', '~> 1.4'
 # Use Puma as the app server
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5'
 # Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker
diff --git a/lessonThree/app/Gemfile.lock b/lessonThree/app/Gemfile.lock
index 889c35b..9c6b8eb 100644
--- a/lessonThree/app/Gemfile.lock
+++ b/lessonThree/app/Gemfile.lock
@@ -289,7 +289,9 @@ GEM
     mime-types (3.3)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2019.1009)
-    mimemagic (0.3.3)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_magick (4.9.5)
     mini_mime (1.0.2)
     mini_portile2 (2.4.0)
@@ -305,7 +307,8 @@ GEM
       json (>= 1, < 3)
     pg (1.1.4)
     public_suffix (4.0.1)
-    puma (3.12.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-proxy (0.6.5)
       rack
@@ -445,7 +448,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   mini_magick (~> 4.9.5)
   pg (~> 1.1.4)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 6.0.0)
   rails-controller-testing
   rails-ujs (~> 0.1.0)