diff --git a/Gemfile b/Gemfile
index 3c0273a..5f06112 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.1'
 # Use postgres as the database for Active Record
 gem 'pg'
 # 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 47762a3..498ccd0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -141,7 +141,9 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (0.9.0)
-    mimemagic (0.3.2)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.1)
     mini_portile2 (2.3.0)
     minitest (5.11.3)
@@ -155,7 +157,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.3)
-    puma (3.12.0)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.5)
     rack-proxy (0.6.5)
       rack
@@ -280,7 +283,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   pg
   pry
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.1)
   redis (~> 4.0)
   rspec-rails