diff --git a/Gemfile b/Gemfile
index 0db53a6..8063567 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,7 +6,7 @@ gem 'rails', '~> 5.0.0', '>= 5.0.0.1'
 # Use postgresql as the database for Active Record
 gem 'pg', '~> 0.18'
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+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 487669d..6d5b33c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -87,7 +87,8 @@ GEM
       method_source (~> 1.0)
     pry-rails (0.3.9)
       pry (>= 0.10.4)
-    puma (3.12.5)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.2.2)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -172,7 +173,7 @@ DEPENDENCIES
   pg (~> 0.18)
   pry
   pry-rails
-  puma (~> 3.0)
+  puma (~> 4.3)
   rails (~> 5.0.0, >= 5.0.0.1)
   sass-rails (~> 5.0)
   spring