diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..b18fd29
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: 'github-actions'
+    directory: '/'
+    schedule:
+      interval: 'weekly'
diff --git a/.github/workflows/push_gem.yml b/.github/workflows/push_gem.yml
new file mode 100644
index 0000000..f662094
--- /dev/null
+++ b/.github/workflows/push_gem.yml
@@ -0,0 +1,46 @@
+name: Publish gem to rubygems.org
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions:
+  contents: read
+
+jobs:
+  push:
+    if: github.repository == 'ruby/ruby2_keywords'
+    runs-on: ubuntu-latest
+
+    environment:
+      name: rubygems.org
+      url: https://rubygems.org/gems/ruby2_keywords
+
+    permissions:
+      contents: write
+      id-token: write
+
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
+        with:
+          egress-policy: audit
+
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
+        with:
+          bundler-cache: true
+          ruby-version: "ruby"
+
+      - name: Publish to RubyGems
+        uses: rubygems/release-gem@a25424ba2ba8b387abc8ef40807c2c85b96cbe32 # v1.1.1
+
+      - name: Create GitHub release
+        run: |
+          tag_name="$(git describe --tags --abbrev=0)"
+          gh release create "${tag_name}" --verify-tag --generate-notes
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..5932c89
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,56 @@
+name: test
+
+on: [push, pull_request]
+
+jobs:
+  ruby-versions:
+    uses: ruby/actions/.github/workflows/ruby_versions.yml@master
+    with:
+      engine: cruby
+      min_version: 2.1
+
+  build:
+    needs: ruby-versions
+    name: build (${{ matrix.ruby }} / ${{ matrix.os }})
+    strategy:
+      matrix:
+        ruby: ${{ fromJson(needs.ruby-versions.outputs.versions) }}
+        os: [ ubuntu-latest, macos-latest, windows-latest ]
+        include:
+          - { os: ubuntu-latest, ruby: truffleruby-head }
+          - { os: macos-latest, ruby: truffleruby-head }
+        exclude:
+        - { os: macos-latest, ruby: 2.1 }
+        - { os: macos-latest, ruby: 2.2 }
+        - { os: macos-latest, ruby: 2.3 }
+        - { os: macos-latest, ruby: 2.4 }
+        - { os: macos-latest, ruby: 2.5 }
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: git config
+      run: |
+        git config --global core.autocrlf false
+        git config --global core.eol lf
+        git config --global advice.detachedHead 0
+    - uses: actions/checkout@master
+    - name: Set up Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby }}
+        bundler-cache: true
+    - name: Run test
+      run: bundle exec rake test
+    - id: build
+      run: |
+        rake build
+        echo "pkg=${GITHUB_REPOSITORY#*/}-${RUNNING_OS%-*}" >> $GITHUB_OUTPUT
+      env:
+        RUNNING_OS: ${{matrix.os}}
+      if: "matrix.ruby == '3.0'"
+      shell: bash
+    - name: Upload package
+      uses: actions/upload-artifact@v4
+      with:
+        path: pkg/*.gem
+        name: ${{steps.build.outputs.pkg}}
+      if: steps.build.outputs.pkg
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..230b7e3
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+ChangeLog
+logs/
+gems.locked
+pkg/
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..3b9d383
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,22 @@
+Copyright 2019-2020 Nobuyoshi Nakada, Yusuke Endoh
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/README.md b/README.md
index f3b56aa..42e1157 100644
--- a/README.md
+++ b/README.md
@@ -42,10 +42,34 @@ ruby2_keywords def oldstyle_keywords(options = {})
 end
 ```
 
+You can do the same for a method defined by `Module#define_method`:
+
+```ruby
+define_method :delegating_method do |*args, &block|
+  other_method(*args, &block)
+end
+ruby2_keywords :delegating_method
+```
+
 ## Contributing
 
-Bug reports and pull requests are welcome on GitHub at https://bugs.ruby-lang.org.
+Bug reports and pull requests are welcome on [GitHub] or
+[Ruby Issue Tracking System].
+
+## Development
+
+After checking out the repo, run `bundle install` to install dependencies.
+Then, run `bundle exec rake test` to run the tests.
+
+To test on older Ruby versions, you can use docker. E.g. to test on Ruby 2.0,
+use `docker-compose run ruby-2.0`.
 
 ## License
 
-The gem is available as open source under the terms of the [2-Clause BSD License](https://opensource.org/licenses/BSD-2-Clause).
+The gem is available as open source under the terms of the
+[Ruby License] or the [2-Clause BSD License].
+
+[GitHub]: https://github.com/ruby/ruby2_keywords/
+[Ruby Issue Tracking System]: https://bugs.ruby-lang.org
+[Ruby License]: https://www.ruby-lang.org/en/about/license.txt
+[2-Clause BSD License]: https://opensource.org/licenses/BSD-2-Clause
diff --git a/Rakefile b/Rakefile
new file mode 100644
index 0000000..caacbf2
--- /dev/null
+++ b/Rakefile
@@ -0,0 +1,16 @@
+require "bundler/gem_tasks"
+require "rake/testtask"
+
+Rake::TestTask.new(:test) do |t|
+  t.test_files = FileList["test/**/test_*.rb"]
+end
+
+task :default => :test
+
+task "bump:minor" do
+  raise "can't bump up minor"
+end
+
+task "bump:major" do
+  raise "can't bump up major"
+end
diff --git a/docker-compose.yml b/docker-compose.yml
new file mode 100644
index 0000000..3135f88
--- /dev/null
+++ b/docker-compose.yml
@@ -0,0 +1,57 @@
+version: '3.0'
+
+services:
+  ruby-2.0:
+    image: ruby:2.0
+    volumes:
+      - .:/app
+    command:
+      bash -c 'cd /app && bundle install && bundle exec rake test'
+  ruby-2.1:
+    image: ruby:2.1
+    volumes:
+      - .:/app
+    command:
+      bash -c 'cd /app && bundle install && bundle exec rake test'
+  ruby-2.2:
+    image: ruby:2.2
+    volumes:
+      - .:/app
+    command:
+      bash -c 'cd /app && bundle install && bundle exec rake test'
+  ruby-2.3:
+    image: ruby:2.3
+    volumes:
+      - .:/app
+    command:
+      bash -c 'cd /app && bundle install && bundle exec rake test'
+  ruby-2.4:
+    image: ruby:2.4
+    volumes:
+      - .:/app
+    command:
+      bash -c 'cd /app && bundle install && bundle exec rake test'
+  ruby-2.5:
+    image: ruby:2.5
+    volumes:
+      - .:/app
+    command:
+      bash -c 'cd /app && bundle install && bundle exec rake test'
+  ruby-2.6:
+    image: ruby:2.6
+    volumes:
+      - .:/app
+    command:
+      bash -c 'cd /app && bundle install && bundle exec rake test'
+  ruby-2.7:
+    image: ruby:2.7
+    volumes:
+      - .:/app
+    command:
+      bash -c 'cd /app && bundle install && bundle exec rake test'
+  ruby-3.0:
+    image: ruby:3.0
+    volumes:
+      - .:/app
+    command:
+      bash -c 'cd /app && bundle install && bundle exec rake test'
diff --git a/gems.rb b/gems.rb
new file mode 100644
index 0000000..2b2a2c4
--- /dev/null
+++ b/gems.rb
@@ -0,0 +1,8 @@
+source 'https://rubygems.org'
+
+gemspec
+
+group :development do
+  gem "test-unit", ">= 2.2"
+  gem "rake"
+end
diff --git a/lib/ruby2_keywords.rb b/lib/ruby2_keywords.rb
index 8c48333..09827b5 100644
--- a/lib/ruby2_keywords.rb
+++ b/lib/ruby2_keywords.rb
@@ -1,14 +1,22 @@
 class Module
-  unless respond_to?(:ruby2_keywords, true)
+  unless private_method_defined?(:ruby2_keywords)
     private
+    # call-seq:
+    #    ruby2_keywords(method_name, ...)
+    #
+    # Does nothing.
     def ruby2_keywords(name, *)
       # nil
     end
   end
 end
 
-main = TOPLEVEL_BINDING.receiver
+main = TOPLEVEL_BINDING.eval('self')
 unless main.respond_to?(:ruby2_keywords, true)
+  # call-seq:
+  #    ruby2_keywords(method_name, ...)
+  #
+  # Does nothing.
   def main.ruby2_keywords(name, *)
     # nil
   end
@@ -16,8 +24,34 @@ def main.ruby2_keywords(name, *)
 
 class Proc
   unless method_defined?(:ruby2_keywords)
+    # call-seq:
+    #    proc.ruby2_keywords -> proc
+    #
+    # Does nothing and just returns the receiver.
     def ruby2_keywords
       self
     end
   end
 end
+
+class << Hash
+  unless method_defined?(:ruby2_keywords_hash?)
+    # call-seq:
+    #    Hash.ruby2_keywords_hash?(hash) -> false
+    #
+    # Returns false.
+    def ruby2_keywords_hash?(hash)
+      false
+    end
+  end
+
+  unless method_defined?(:ruby2_keywords_hash)
+    # call-seq:
+    #    Hash.ruby2_keywords_hash(hash) -> new_hash
+    #
+    # Duplicates a given hash and returns the new hash.
+    def ruby2_keywords_hash(hash)
+      hash.dup
+    end
+  end
+end
diff --git a/rakelib/changelogs.rake b/rakelib/changelogs.rake
new file mode 100644
index 0000000..df72f9d
--- /dev/null
+++ b/rakelib/changelogs.rake
@@ -0,0 +1,34 @@
+task "build" => "changelogs"
+
+changelog = proc do |output, ver = nil, prev = nil|
+  ver &&= Gem::Version.new(ver)
+  range = [[prev], [ver, "HEAD"]].map {|ver, branch| ver ? "v#{ver.to_s}" : branch}.compact.join("..")
+  IO.popen(%W[git log --format=fuller --topo-order --no-merges #{range}]) do |log|
+    line = log.gets
+    FileUtils.mkpath(File.dirname(output))
+    File.open(output, "wb") do |f|
+      f.print "-*- coding: utf-8 -*-\n\n", line
+      log.each_line do |line|
+        line.sub!(/^(?!:)(?:Author|Commit)?(?:Date)?: /, '  \&')
+        line.sub!(/ +$/, '')
+        f.print(line)
+      end
+    end
+  end
+end
+
+tags = IO.popen(%w[git tag -l v[0-9]*]).grep(/v(.*)/) {$1}
+tags.sort_by! {|tag| tag.scan(/\d+/).map(&:to_i)}
+tags.inject(nil) do |prev, tag|
+  task("logs/ChangeLog-#{tag}") {|t| changelog[t.name, tag, prev]}
+  tag
+end
+
+desc "Make ChangeLog"
+task "ChangeLog", [:ver, :prev] do |t, ver: nil, prev: tags.last|
+  changelog[t.name, ver, prev]
+end
+
+changelogs = ["ChangeLog", *tags.map {|tag| "logs/ChangeLog-#{tag}"}]
+task "changelogs" => changelogs
+CLOBBER.concat(changelogs) << "logs"
diff --git a/rakelib/epoch.rake b/rakelib/epoch.rake
new file mode 100644
index 0000000..80f27c9
--- /dev/null
+++ b/rakelib/epoch.rake
@@ -0,0 +1,5 @@
+task "build" => "date_epoch"
+
+task "date_epoch" do
+  ENV["SOURCE_DATE_EPOCH"] = IO.popen(%W[git -C #{__dir__} log -1 --format=%ct], &:read).chomp
+end
diff --git a/rakelib/version.rake b/rakelib/version.rake
new file mode 100644
index 0000000..bbb327f
--- /dev/null
+++ b/rakelib/version.rake
@@ -0,0 +1,44 @@
+class << (helper = Bundler::GemHelper.instance)
+  def update_gemspec
+    path = gemspec.loaded_from
+    File.open(path, "r+b") do |f|
+      d = f.read
+      if d.sub!(/^(_VERSION\s*=\s*)".*"/) {$1 + gemspec.version.to_s.dump}
+        f.rewind
+        f.truncate(0)
+        f.print(d)
+      end
+    end
+  end
+
+  def commit_bump
+    sh(%W[git commit -m bump\ up\ to\ #{gemspec.version}
+          #{gemspec.loaded_from}])
+  end
+
+  def version=(v)
+    gemspec.version = v
+    update_gemspec
+    commit_bump
+  end
+end
+
+major, minor, teeny = helper.gemspec.version.segments
+
+task "bump:teeny" do
+  helper.version = Gem::Version.new("#{major}.#{minor}.#{teeny+1}")
+end
+
+task "bump:minor" do
+  helper.version = Gem::Version.new("#{major}.#{minor+1}.0")
+end
+
+task "bump:major" do
+  helper.version = Gem::Version.new("#{major+1}.0.0")
+end
+
+task "bump" => "bump:teeny"
+
+task "tag" do
+  helper.__send__(:tag_version)
+end
diff --git a/ruby2_keywords.gemspec b/ruby2_keywords.gemspec
index 623c58c..e2cd397 100644
--- a/ruby2_keywords.gemspec
+++ b/ruby2_keywords.gemspec
@@ -1,16 +1,23 @@
-version = IO.popen(%W[git -C #{__dir__} describe --tags --match v[0-9]*], &:read)[/\Av?(\d+(?:\.\d+)*)/, 1]
+_VERSION = "0.0.5"
+abort "Version must not reach 1" if _VERSION[/\d+/].to_i >= 1
 
 Gem::Specification.new do |s|
   s.name = "ruby2_keywords"
-  s.version = version
+  s.version = _VERSION
   s.summary = "Shim library for Module#ruby2_keywords"
   s.homepage = "https://github.com/ruby/ruby2_keywords"
-  s.licenses = ["Ruby"]
+  s.licenses = ["Ruby", "BSD-2-Clause"]
   s.authors = ["Nobuyoshi Nakada"]
   s.require_paths = ["lib"]
-  s.files = [
+  s.rdoc_options = ["--main", "README.md"]
+  s.extra_rdoc_files = [
+    "LICENSE",
     "README.md",
+    "ChangeLog",
+    *Dir.glob("#{__dir__}/logs/ChangeLog-*[^~]").map {|path| path[(__dir__.size+1)..-1]},
+  ]
+  s.files = [
     "lib/ruby2_keywords.rb",
-    "ruby2_keywords.gemspec",
   ]
+  s.required_ruby_version = '>= 2.0.0'
 end
diff --git a/test/test_keyword.rb b/test/test_keyword.rb
new file mode 100644
index 0000000..13d6041
--- /dev/null
+++ b/test/test_keyword.rb
@@ -0,0 +1,41 @@
+require 'test/unit'
+LOADING_RUBY2_KEYWORDS = (RUBY_VERSION.scan(/\d+/).map(&:to_i) <=> [2, 7]) < 0
+if LOADING_RUBY2_KEYWORDS
+  require 'ruby2_keywords'
+end
+
+class TestKeywordArguments < Test::Unit::TestCase
+  def test_loaded_features
+    list = $LOADED_FEATURES.grep(%r[/ruby2_keywords\.rb\z])
+    if LOADING_RUBY2_KEYWORDS
+      assert_not_empty(list)
+      assert_not_include($LOADED_FEATURES, "ruby2_keywords.rb")
+    else
+      assert_empty(list)
+      assert_include($LOADED_FEATURES, "ruby2_keywords.rb")
+    end
+  end
+
+  def test_module_ruby2_keywords
+    assert_send([Module, :private_method_defined?, :ruby2_keywords])
+    assert_operator(Module.instance_method(:ruby2_keywords).arity, :<, 0)
+  end
+
+  def test_toplevel_ruby2_keywords
+    main = TOPLEVEL_BINDING.eval('self')
+    assert_send([main, :respond_to?, :ruby2_keywords, true])
+    assert_operator(main.method(:ruby2_keywords).arity, :<, 0)
+  end
+
+  def test_proc_ruby2_keywords
+    assert_respond_to(Proc.new {}, :ruby2_keywords)
+  end
+
+  def test_hash_ruby2_keywords_hash?
+    assert_false(Hash.ruby2_keywords_hash?({}))
+  end
+
+  def test_hash_ruby2_keywords_hash
+    assert_equal({}, Hash.ruby2_keywords_hash({}.freeze))
+  end
+end