diff --git a/Gemfile b/Gemfile
index 57d14b9..ca8da48 100644
--- a/Gemfile
+++ b/Gemfile
@@ -10,7 +10,7 @@ end
 gem 'rails', '~> 5.1.2'
 
 # Use Puma as the app server
-gem 'puma', '~> 3.7'
+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 f128b2a..4e3896c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -120,7 +120,8 @@ GEM
       method_source (~> 0.8.1)
       slop (~> 3.4)
     public_suffix (2.0.5)
-    puma (3.10.0)
+    puma (4.3.3)
+      nio4r (~> 2.0)
     rack (2.0.3)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -238,7 +239,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   pg
   pry
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.1.2)
   rspec-rails (~> 3.6)
   sass-rails (~> 5.0)