diff --git a/Gemfile b/Gemfile
index 60df2e3..8e9b2cf 100644
--- a/Gemfile
+++ b/Gemfile
@@ -30,7 +30,7 @@ gem "mini_racer"
 # Use pry for debugging
 gem "pry"
 # Use Puma as the app server
-gem "puma", "~> 3.12"
+gem "puma", "~> 4.3"
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem "rails", "~> 5.1.6"
 # Use Redis adapter to run Action Cable in production
diff --git a/Gemfile.lock b/Gemfile.lock
index 3b861f6..11dc32b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -149,7 +149,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.3)
-    puma (3.12.6)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -263,7 +264,7 @@ DEPENDENCIES
   nokogiri (>= 1.8.5)
   pg
   pry
-  puma (~> 3.12)
+  puma (~> 4.3)
   rack (>= 2.0.6)
   rails (~> 5.1.6)
   rails_12factor