diff --git a/Gemfile b/Gemfile
index 2ed85bd..0318edb 100644
--- a/Gemfile
+++ b/Gemfile
@@ -15,7 +15,7 @@ gem 'mini_magick'
 gem 'fog'
 gem 'mi'
 # 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 9bcefd8..9dd8d28 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -310,7 +310,8 @@ GEM
       json (>= 1, < 3)
     pg (1.1.4)
     public_suffix (3.1.0)
-    puma (3.12.1)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -441,7 +442,7 @@ DEPENDENCIES
   mi
   mini_magick
   pg
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.1.7)
   sass-rails (~> 5.0)
   selenium-webdriver