diff --git a/Gemfile b/Gemfile
index 326c937..c8eb5eb 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.3'
 # bootstrap as our css library
 gem 'bootstrap-sass', '3.4.1'
 # 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 5158814..d21a527 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -123,7 +123,9 @@ 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 (1.0.2)
     mini_portile2 (2.4.0)
     minitest (5.10.3)
@@ -145,7 +147,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.1.1)
-    puma (3.12.1)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -255,7 +258,7 @@ DEPENDENCIES
   minitest (= 5.10.3)
   minitest-reporters (= 1.1.14)
   pg (= 0.20.0)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   rails-controller-testing (= 1.0.2)
   sass-rails (~> 5.0)