diff --git a/Gemfile b/Gemfile
index e5b7dc0..e8b2025 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,7 +13,7 @@ gem 'rails', '~> 5.1.4'
 # gem 'sqlite3'
 gem 'pg'
 # Use Puma as the app server
-gem 'puma', '~> 3.7'
+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 91a3ba9..86c6f66 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -113,7 +113,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.1)
-    puma (3.11.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.4)
     rack-test (0.8.2)
       rack (>= 1.0, < 3)
@@ -216,7 +217,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   pg
   pry
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.1.4)
   sass-rails (~> 5.0)
   selenium-webdriver