diff --git a/Gemfile b/Gemfile
index 48c3140..f3a295c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,7 +7,7 @@ end
 
 gem 'rails', '~> 5.1.4'
 gem 'pg', '~> 0.18'
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 gem 'sass-rails', '~> 5.0'
 gem 'uglifier', '>= 1.3.0'
 gem 'webpush'
diff --git a/Gemfile.lock b/Gemfile.lock
index a58feb3..d369597 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -114,7 +114,8 @@ GEM
     pry-rails (0.3.6)
       pry (>= 0.10.4)
     public_suffix (3.0.2)
-    puma (3.12.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-cors (1.0.5)
       rack (>= 1.6.0)
@@ -213,7 +214,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   pg (~> 0.18)
   pry-rails
-  puma (~> 3.12)
+  puma (~> 4.3)
   rack-cors
   rails (~> 5.1.4)
   sass-rails (~> 5.0)