diff --git a/Gemfile b/Gemfile
index 91d46bc..02ff4a4 100644
--- a/Gemfile
+++ b/Gemfile
@@ -10,7 +10,7 @@ gem 'rails', '~> 5.2.3'
 # Use postgres as the database for Active Record
 gem 'pg'
 # 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 e2b8647..4e457cd 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -142,8 +142,10 @@ GEM
     pg (1.1.4-x86-mingw32)
     popper_js (1.14.5)
     public_suffix (3.1.0)
-    puma (3.12.2)
-    puma (3.12.2-java)
+    puma (4.3.11)
+      nio4r (~> 2.0)
+    puma (4.3.11-java)
+      nio4r (~> 2.0)
     rack (2.1.2)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -268,7 +270,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   mail_form
   pg
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   rubocop
   sass-rails (~> 5.0)