diff --git a/challenges/EzGrammar/Gemfile b/challenges/EzGrammar/Gemfile
index d4019c8..62df59a 100644
--- a/challenges/EzGrammar/Gemfile
+++ b/challenges/EzGrammar/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.0'
 # Use mysql as the database for Active Record
 gem 'mysql2', '>= 0.4.4', '< 0.6.0'
 # 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/challenges/EzGrammar/Gemfile.lock b/challenges/EzGrammar/Gemfile.lock
index 0704f30..97a137b 100644
--- a/challenges/EzGrammar/Gemfile.lock
+++ b/challenges/EzGrammar/Gemfile.lock
@@ -117,7 +117,9 @@ GEM
     mime-types (3.1)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2016.0521)
-    mimemagic (0.3.2)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.0)
     mini_portile2 (2.3.0)
     minitest (5.11.3)
@@ -128,7 +130,8 @@ GEM
     nokogiri (1.8.4)
       mini_portile2 (~> 2.3.0)
     public_suffix (3.0.2)
-    puma (3.12.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.5)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -226,7 +229,7 @@ DEPENDENCIES
   jquery-rails
   listen (>= 3.0.5, < 3.2)
   mysql2 (>= 0.4.4, < 0.6.0)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.0)
   sass-rails (~> 5.0)
   selenium-webdriver