diff --git a/Gemfile b/Gemfile
index 8b6496b..aadd587 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ gem 'rails', '~> 5.1.7'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3','~>1.3.13'
 # 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 1b25412..42ed1fa 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -95,7 +95,8 @@ GEM
       mini_portile2 (~> 2.4.0)
     orm_adapter (0.5.0)
     public_suffix (4.0.2)
-    puma (3.12.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -189,7 +190,7 @@ DEPENDENCIES
   coffee-rails (~> 4.2)
   devise
   jbuilder (~> 2.5)
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.1.7)
   sass-rails (~> 5.0)
   selenium-webdriver