diff --git a/Gemfile b/Gemfile
index adf2f00..a2ee189 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 6.0.0'
 # Use sqlite3 as the database for Active Record
 gem 'mysql2' # , '0.3.20'
 # 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/Gemfile.lock b/Gemfile.lock
index 3e7f4bd..c2e379c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -165,7 +165,9 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (1.0.0)
-    mimemagic (0.3.5)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.2)
     mini_portile2 (2.4.0)
     minitest (5.14.0)
@@ -179,7 +181,8 @@ GEM
       activerecord (>= 5.2.1)
     popper_js (1.16.0)
     public_suffix (4.0.4)
-    puma (3.12.4)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     rack (2.2.2)
     rack-proxy (0.6.5)
       rack
@@ -316,7 +319,7 @@ DEPENDENCIES
   jbuilder (~> 2.7)
   listen (>= 3.0.5, < 3.2)
   mysql2
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 6.0.0)
   rails-erd
   redcarpet