diff --git a/Gemfile b/Gemfile
index ed422a3..1e463a8 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ gem 'rails', '~> 5.2.3'
 gem 'sqlite3', group: :development
 gem 'pg', group: :production
 # 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 1ab0657..3ee4a91 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -142,7 +142,9 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (0.9.2)
-    mimemagic (0.3.3)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.1)
     mini_portile2 (2.4.0)
     minitest (5.11.3)
@@ -158,7 +160,8 @@ GEM
     pg (1.1.4)
     popper_js (1.14.5)
     public_suffix (3.1.0)
-    puma (3.12.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-protection (2.0.5)
       rack
@@ -288,7 +291,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   momentjs-rails
   pg
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   sass-rails (~> 5.0)
   selenium-webdriver