diff --git a/Gemfile b/Gemfile
index a6eb94d..346d82c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'rails', '~> 5.2.0'
 # Use sqlite3 as the database for Active Record
 gem 'mysql2'
 # Use Puma as the app server
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 3.12'
 # 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 88d8399..e60aa04 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -113,7 +113,7 @@ GEM
     nokogiri (1.8.4)
       mini_portile2 (~> 2.3.0)
     public_suffix (3.0.2)
-    puma (3.12.0)
+    puma (3.12.6)
     rack (2.0.5)
     rack-test (1.0.0)
       rack (>= 1.0, < 3)
@@ -209,7 +209,7 @@ DEPENDENCIES
   line-bot-api
   listen (>= 3.0.5, < 3.2)
   mysql2
-  puma (~> 3.11)
+  puma (~> 3.12)
   rails (~> 5.2.0)
   sass-rails (~> 5.0)
   selenium-webdriver