diff --git a/Gemfile b/Gemfile
index ad9894c..a5a1190 100644
--- a/Gemfile
+++ b/Gemfile
@@ -24,7 +24,7 @@ end
 
 
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+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 19d58c5..a087b4b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -105,7 +105,9 @@ GEM
     mime-types (3.1)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2016.0521)
-    mimemagic (0.3.2)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_portile2 (2.3.0)
     minitest (5.10.3)
     multi_json (1.12.2)
@@ -140,7 +142,8 @@ GEM
     pry (0.11.1)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
-    puma (3.10.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.3)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -247,7 +250,7 @@ DEPENDENCIES
   paperclip
   pg
   pry
-  puma (~> 3.0)
+  puma (~> 4.3)
   rails (~> 5.0.4)
   rails_12factor
   record_tag_helper (~> 1.0)