diff --git a/Gemfile b/Gemfile
index b13895a..daffd22 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,7 +2,7 @@ source 'https://rubygems.org'
 ruby '2.4.1'
 
 # HTTP server for Ruby/Rack recommended by Heroku
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 3.12'
 
 # Middleman
 gem 'middleman', '~> 4.2', '>= 4.2.1'
diff --git a/Gemfile.lock b/Gemfile.lock
index 6a9b5f5..3f9aa96 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -97,7 +97,7 @@ GEM
       activesupport (>= 3.1)
     parallel (1.12.1)
     public_suffix (3.0.2)
-    puma (3.11.3)
+    puma (3.12.0)
     rack (1.6.10)
     rack-contrib (1.8.0)
       rack (~> 1.4)
@@ -135,7 +135,7 @@ DEPENDENCIES
   middleman-livereload (~> 3.4, >= 3.4.6)
   middleman-sprockets (~> 4.1)
   middleman-syntax (= 3.0.0)
-  puma (~> 3.11)
+  puma (~> 3.12)
   rack-contrib (~> 1.5)
   redcarpet (= 3.4.0)
   slim (~> 3.0, >= 3.0.8)