diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index b79ea7d..c5c461c 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,4 +1,4 @@
-name: ubuntu
+name: test
 
 on: [push, pull_request]
 
@@ -7,10 +7,15 @@ jobs:
     name: build (${{ matrix.ruby }} / ${{ matrix.os }})
     strategy:
       matrix:
-        ruby: [ '3.0', 2.7, 2.6, head ]
+        ruby: [ '3.0', 2.7, 2.6, 2.5, head ]
         os: [ ubuntu-latest, macos-latest, windows-latest ]
     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
@@ -18,3 +23,17 @@ jobs:
         ruby-version: ${{ matrix.ruby }}
     - name: Run test
       run: rake test
+    - id: build
+      run: |
+        rake build
+        echo "::set-output name=pkg::${GITHUB_REPOSITORY#*/}-${RUNNING_OS%-*}"
+      env:
+        RUNNING_OS: ${{matrix.os}}
+      if: "matrix.ruby == '3.0'"
+      shell: bash
+    - name: Upload package
+      uses: actions/upload-artifact@v2
+      with:
+        path: pkg/*.gem
+        name: ${{steps.build.outputs.pkg}}
+      if: steps.build.outputs.pkg
diff --git a/Rakefile b/Rakefile
index 8830e05..6eb5091 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,8 +1,54 @@
 require "bundler/gem_tasks"
 require "rake/testtask"
 
+helper = Bundler::GemHelper.instance
+
 Rake::TestTask.new(:test) do |t|
   t.test_files = FileList["test/**/test_*.rb"]
 end
 
 task :default => :test
+
+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
+
+def helper.update_gemspec
+  path = "#{__dir__}/#{gemspec.name}.gemspec"
+  File.open(path, "r+b") do |f|
+    if (d = f.read).sub!(/^(version\s*=\s*)".*"/) {$1 + gemspec.version.to_s.dump}
+      f.rewind
+      f.truncate(0)
+      f.print(d)
+    end
+  end
+end
+
+def helper.commit_bump
+  sh(%W[git -C #{__dir__} commit -m bump\ up\ to\ #{gemspec.version}
+        #{gemspec.name}.gemspec])
+end
+
+def helper.version=(v)
+  gemspec.version = v
+  update_gemspec
+  commit_bump
+  tag_version
+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
+  raise "can't bump up minor"
+end
+
+task "bump:major" do
+  raise "can't bump up major"
+end
+
+task "bump" => "bump:teeny"
diff --git a/lib/ruby2_keywords.rb b/lib/ruby2_keywords.rb
index 97cd081..7a3f2fa 100644
--- a/lib/ruby2_keywords.rb
+++ b/lib/ruby2_keywords.rb
@@ -1,5 +1,5 @@
 class Module
-  unless private_method_defined?(:ruby2_keywords, true)
+  unless private_method_defined?(:ruby2_keywords)
     private
     # call-seq:
     #    ruby2_keywords(method_name, ...)
diff --git a/ruby2_keywords.gemspec b/ruby2_keywords.gemspec
index 5eac57b..8247998 100644
--- a/ruby2_keywords.gemspec
+++ b/ruby2_keywords.gemspec
@@ -1,4 +1,4 @@
-version = "0.0.3"
+version = "0.0.4"
 abort "Version must not reach 1" if version[/\d+/].to_i >= 1
 
 Gem::Specification.new do |s|