diff --git a/Gemfile b/Gemfile
index cbe545f..e206532 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,7 +6,7 @@ gem 'rails', '~> 5.2.1'
 # Use sqlite3 as the database for Active Record
 gem 'pg'
 # Use Puma as the app server
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 # Use Redis adapter to run Action Cable in production
 # gem 'redis', '~> 4.0'
 # Use ActiveModel has_secure_password
diff --git a/Gemfile.lock b/Gemfile.lock
index c532ba2..bc65abf 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -104,7 +104,9 @@ 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)
     mini_racer (0.2.6)
@@ -121,7 +123,8 @@ GEM
     pry-rails (0.3.9)
       pry (>= 0.10.4)
     public_suffix (3.1.0)
-    puma (3.12.6)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     rack (2.2.3)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -246,7 +249,7 @@ DEPENDENCIES
   mini_racer
   pg
   pry-rails
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.2.1)
   rails-controller-testing
   rspec-rails (~> 3.8)