diff --git a/Gemfile b/Gemfile
index be415d9..2b14d48 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.0'
 # 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/Gemfile.lock b/Gemfile.lock
index 8e6cef6..71b1db4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -105,7 +105,9 @@ 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 (5.14.1)
@@ -115,7 +117,8 @@ GEM
       mini_portile2 (~> 2.4.0)
     popper_js (1.16.0)
     public_suffix (4.0.5)
-    puma (3.12.6)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     rack (2.2.2)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -219,7 +222,7 @@ DEPENDENCIES
   jbuilder (~> 2.5)
   jquery-rails (~> 4.3.5)
   listen (>= 3.0.5, < 3.2)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.0)
   sass-rails (~> 5.0)
   selenium-webdriver