diff --git a/Gemfile b/Gemfile
index 0fde2af..efdece1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.0.0', '>= 5.0.0.1'
 # Use PostgreSQL for Heroku database
 gem 'pg'
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 4.3'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
 # gem 'jbuilder', '~> 2.5'
 # Use Redis adapter to run Action Cable in production
diff --git a/Gemfile.lock b/Gemfile.lock
index b7a2965..bc1ae03 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -132,7 +132,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.3)
-    puma (3.12.0)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-cors (1.0.2)
     rack-test (0.6.3)
@@ -224,7 +225,7 @@ DEPENDENCIES
   omniauth
   omniauth-cas
   pg
-  puma (~> 3.0)
+  puma (~> 4.3)
   rack-cors
   rails (~> 5.0.0, >= 5.0.0.1)
   rspec-rails