diff --git a/Gemfile b/Gemfile
index 4a528d1..ddc4ed0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -12,7 +12,7 @@ gem 'rails', '~> 5.1.7'
 # Use postgresql as the database for Active Record
 gem 'pg', '>= 0.18', '< 2.0'
 # Use Puma as the app server
-gem 'puma', '~> 3.12'
+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 683e716..2de938a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -89,7 +89,8 @@ GEM
     pg (1.1.4)
     popper_js (1.14.5)
     public_suffix (4.0.1)
-    puma (3.12.2)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-proxy (0.6.5)
       rack
@@ -192,7 +193,7 @@ DEPENDENCIES
   font-awesome-sass (~> 5.2.0)
   listen (>= 3.0.5, < 3.2)
   pg (>= 0.18, < 2.0)
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.1.7)
   sass-rails (~> 5.0)
   selenium-webdriver