diff --git a/Gemfile b/Gemfile
index d77e4e4..2b67989 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ gem 'rails', '~> 5.2.4'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # 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 a2e39d2..b3d8bce 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -127,7 +127,8 @@ GEM
     orm_adapter (0.5.0)
     popper_js (1.14.5)
     public_suffix (4.0.1)
-    puma (3.12.4)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -241,7 +242,7 @@ DEPENDENCIES
   jbuilder (~> 2.5)
   listen (>= 3.0.5, < 3.2)
   mysql2 (= 0.5.2)
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.2.4)
   sass-rails (~> 5.0)
   selenium-webdriver