diff --git a/Gemfile b/Gemfile
index 0ea6e1f..b97924c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,7 +13,7 @@ gem 'rails', '~> 5.0.1'
 gem 'pg'
 # gem 'sqlite3'
 # 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 4318fd7..42aaa3e 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -96,7 +96,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
       slop (~> 3.4)
-    puma (3.8.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.1)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -202,7 +203,7 @@ DEPENDENCIES
   listen (~> 3.0.5)
   pg
   pry
-  puma (~> 3.0)
+  puma (~> 4.3)
   rails (~> 5.0.1)
   rspec-rails (~> 3.5)
   sass-rails (~> 5.0)