diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f313947e..50ccc50b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,10 +14,10 @@ jobs:
     strategy:
       matrix:
         ruby:
-          - "3.0"
           - "3.1"
           - "3.2"
           - "3.3"
+          - "3.4"
       fail-fast: false
 
     steps:
diff --git a/Gemfile b/Gemfile
index e2c29f9c..bcd13f88 100644
--- a/Gemfile
+++ b/Gemfile
@@ -15,3 +15,4 @@ gem "twitter-text", "~> 1.14"
 gem "asciidoctor", "~> 2.0.5"
 gem "rake"
 gem "rexml"
+gem "nokogiri", "~> 1.18.4"
diff --git a/Gemfile.lock b/Gemfile.lock
index c8c61181..23db3a13 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -55,19 +55,21 @@ GEM
       concurrent-ruby (~> 1.0)
     logger (1.7.0)
     mini_mime (1.1.5)
+    mini_portile2 (2.8.8)
     minitest (5.25.5)
     mutex_m (0.3.0)
-    nokogiri (1.17.2-aarch64-linux)
+    nokogiri (1.18.7)
+      mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
-    nokogiri (1.17.2-arm-linux)
+    nokogiri (1.18.7-aarch64-linux-gnu)
       racc (~> 1.4)
-    nokogiri (1.17.2-arm64-darwin)
+    nokogiri (1.18.7-arm-linux-gnu)
       racc (~> 1.4)
-    nokogiri (1.17.2-x86-linux)
+    nokogiri (1.18.7-arm64-darwin)
       racc (~> 1.4)
-    nokogiri (1.17.2-x86_64-darwin)
+    nokogiri (1.18.7-x86_64-darwin)
       racc (~> 1.4)
-    nokogiri (1.17.2-x86_64-linux)
+    nokogiri (1.18.7-x86_64-linux-gnu)
       racc (~> 1.4)
     nokogiri-diff (0.3.0)
       nokogiri (~> 1.5)
@@ -126,7 +128,7 @@ DEPENDENCIES
   html-pipeline (~> 1.0)
   kramdown
   minitest (~> 5.4, >= 5.4.3)
-  nokogiri (~> 1.17.2)
+  nokogiri (~> 1.18.4)
   nokogiri-diff (~> 0.3.0)
   org-ruby (= 0.9.12)
   rake
diff --git a/github-markup.gemspec b/github-markup.gemspec
index ddd4635f..4329a901 100644
--- a/github-markup.gemspec
+++ b/github-markup.gemspec
@@ -13,7 +13,7 @@ Gem::Specification.new do |s|
   s.homepage      = "https://github.com/github/markup"
   s.license       = "MIT"
 
-  s.required_ruby_version = '>= 3.0.0'
+  s.required_ruby_version = '>= 3.1.0'
 
   s.files         = `git ls-files`.split($\)
   s.executables   = s.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
@@ -25,7 +25,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'minitest', '~> 5.4', '>= 5.4.3'
   s.add_development_dependency 'html-pipeline', '~> 1.0'
   s.add_development_dependency 'sanitize', '>= 4.6.3'
-  s.add_development_dependency 'nokogiri', '~> 1.17.2'
+  s.add_development_dependency 'nokogiri', '~> 1.18.4'
   s.add_development_dependency 'nokogiri-diff', '~> 0.3.0'
   s.add_development_dependency "github-linguist", ">= 7.1.3"
 end