diff --git a/Gemfile b/Gemfile
index 37812c8..ac05805 100644
--- a/Gemfile
+++ b/Gemfile
@@ -10,7 +10,7 @@ end
 gem 'rails', '~> 5.0.1'
 gem 'rb-readline'
 gem 'pg', '~> 0.18'
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 5.5'
 gem 'sass-rails', '~> 5.0'
 gem 'uglifier', '>= 1.3.0'
 gem 'coffee-rails', '~> 4.2'
diff --git a/Gemfile.lock b/Gemfile.lock
index 3ab0fb3..703723c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -142,7 +142,8 @@ GEM
     orm_adapter (0.5.0)
     pg (0.21.0)
     public_suffix (3.0.3)
-    puma (3.12.0)
+    puma (5.5.1)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-protection (2.0.4)
       rack
@@ -290,7 +291,7 @@ DEPENDENCIES
   launchy
   listen (~> 3.0.5)
   pg (~> 0.18)
-  puma (~> 3.0)
+  puma (~> 5.5)
   rails (~> 5.0.1)
   rails-controller-testing
   rails_12factor