diff --git a/Gemfile b/Gemfile
index 5b58ec7..412eda4 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ end
 gem 'rails', '~> 5.1.1'
 gem 'pg', '~> 0.18'
 
-gem 'puma', '~> 3.7'
+gem 'puma', '~> 4.3'
 
 gem 'sass-rails', '~> 5.0'
 gem 'uglifier', '>= 1.3.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 3a0fab1..553f3c6 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -102,7 +102,8 @@ GEM
       mini_portile2 (~> 2.1.0)
     pg (0.20.0)
     public_suffix (2.0.5)
-    puma (3.8.2)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     rack (2.0.3)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -197,7 +198,7 @@ DEPENDENCIES
   haml (~> 5.0)
   listen (>= 3.0.5, < 3.2)
   pg (~> 0.18)
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.1.1)
   rspec-rails (~> 3.5)
   sass-rails (~> 5.0)