diff --git a/Gemfile b/Gemfile
index a811c90..f29afe0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -21,7 +21,7 @@ group :development do
   gem "binding_of_caller"
 end
 
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 4.3'
 gem 'sass-rails'
 gem 'jquery-rails'
 gem 'jquery-ui-rails'
diff --git a/Gemfile.lock b/Gemfile.lock
index 086c682..a9ef908 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -142,7 +142,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (4.0.2)
-    puma (3.12.2)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -229,7 +230,7 @@ DEPENDENCIES
   jquery-ui-rails
   omniauth-twitter
   pg
-  puma (~> 3.0)
+  puma (~> 4.3)
   rails (~> 5.0.0)
   sass-rails
   sqlite3 (~> 1.3, < 1.4)