diff --git a/Gemfile b/Gemfile
index bea9f5d..5e81257 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.0.6'
 # Use postgresql as the database for Active Record
 gem 'pg', '~> 0.18'
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 4.3'
 gem 'bootstrap-sass', '~> 3.3.6'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 4446152..0f8dfb1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -89,7 +89,8 @@ GEM
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
     pg (0.21.0)
-    puma (3.10.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.3)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -173,7 +174,7 @@ DEPENDENCIES
   jquery-rails
   listen (~> 3.0.5)
   pg (~> 0.18)
-  puma (~> 3.0)
+  puma (~> 4.3)
   rails (~> 5.0.6)
   sass-rails (~> 5.0)
   spring