diff --git a/Gemfile b/Gemfile
index 7e00a44..79d44b1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,5 +13,5 @@ gem 'middleman-deploy',         git: 'https://github.com/middleman-contrib/middl
 gem 'middleman-sitemap',        git: 'https://github.com/matsu911/middleman-sitemap', branch: 'master'
 
 gem 'builder',                  '~> 3.2.2'  # for feed.xml.builder
-gem 'nokogiri',                 '~> 1.11.0' # for feed.xml builder
+gem 'nokogiri',                 '~> 1.12.5' # for feed.xml builder
 gem 'slim',                     '~> 3.0.6'
diff --git a/Gemfile.lock b/Gemfile.lock
index 65d9677..fbb44ed 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -98,13 +98,13 @@ GEM
       middleman-core (>= 3.2)
     middleman-robots (1.2.3)
       middleman (>= 4.0)
-    mini_portile2 (2.5.1)
+    mini_portile2 (2.6.1)
     minitest (5.14.1)
     net-sftp (2.1.2)
       net-ssh (>= 2.6.5)
     net-ssh (4.1.0)
-    nokogiri (1.11.0)
-      mini_portile2 (~> 2.5.0)
+    nokogiri (1.12.5)
+      mini_portile2 (~> 2.6.1)
       racc (~> 1.4)
     padrino-helpers (0.13.3.4)
       i18n (~> 0.6, >= 0.6.7)
@@ -147,7 +147,7 @@ DEPENDENCIES
   middleman-minify-html (~> 3.4.1)
   middleman-robots (~> 1.2.3)
   middleman-sitemap!
-  nokogiri (~> 1.11.0)
+  nokogiri (~> 1.12.5)
   slim (~> 3.0.6)
 
 BUNDLED WITH