diff --git a/Gemfile b/Gemfile
index 3f15ed1..e35201c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,7 +7,7 @@ end
 
 gem 'rails', '~> 5.1.3'
 gem 'sqlite3', '~> 1.3.6'
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 gem 'sass-rails', '~> 5.0'
 gem 'uglifier', '>= 1.3.0'
 gem 'coffee-rails', '~> 4.2'
diff --git a/Gemfile.lock b/Gemfile.lock
index 788991c..71039e3 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -97,7 +97,8 @@ GEM
       mini_portile2 (~> 2.4.0)
     orm_adapter (0.5.0)
     public_suffix (4.0.3)
-    puma (3.12.4)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -195,7 +196,7 @@ DEPENDENCIES
   devise
   haml
   jbuilder (~> 2.5)
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.1.3)
   sass-rails (~> 5.0)
   selenium-webdriver