diff --git a/Gemfile b/Gemfile
index 48ee7ef..92864fd 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,7 +5,7 @@ ruby ">= 2.3.0"
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.0.0', '>= 5.0.0.1'
 # 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 ee45f83..45ab633 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -103,7 +103,8 @@ GEM
       mini_portile2 (~> 2.4.0)
     orm_adapter (0.5.0)
     pg (0.18.4)
-    puma (3.12.1)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-cors (1.0.3)
     rack-test (0.6.3)
@@ -212,7 +213,7 @@ DEPENDENCIES
   jquery-rails
   listen (~> 3.0.5)
   pg (= 0.18.4)
-  puma (~> 3.0)
+  puma (~> 4.3)
   rack-cors
   rails (~> 5.0.0, >= 5.0.0.1)
   rspec-rails (~> 3.5)