diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 4df8dfb..781dd3d 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -3,7 +3,7 @@ name: Ruby
 on: [push,pull_request]
 
 jobs:
-  build:
+  test:
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
@@ -11,14 +11,32 @@ jobs:
         ruby: [ '2.7', '3.0', '3.1', '3.2' ]
     name: Ruby ${{ matrix.ruby }}
     steps:
-    - uses: actions/checkout@v3
-    - name: Set up Ruby
-      uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby }}
-        bundler-cache: true
-    - name: Run the default task
-      run: |
-        rake build
-        gem install ./pkg/fluent-plugin-utmpx*.gem
-        TESTOPTS="--verbose" bundle exec rake
+      - uses: actions/checkout@v3
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - name: Run the default task
+        run: |
+          TESTOPTS="--verbose" bundle exec rake
+
+  gem:
+    runs-on: ubuntu-latest
+    name: Gem test
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 3.2
+      - name: Install
+        run: |
+          rake install
+          gem install test-unit webrick
+      - name: Test
+        run: |
+          mkdir -p tmp
+          cd tmp
+          cp -a ../test/ ./
+          test/run.rb
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9552bdf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+/tmp/
+/pkg/
+/Gemfile.lock
diff --git a/Rakefile b/Rakefile
index 9756c6e..d8f0379 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,13 +1,7 @@
-require "bundler"
-Bundler::GemHelper.install_tasks
+require "bundler/gem_tasks"
 
-require "rake/testtask"
-
-Rake::TestTask.new(:test) do |t|
-  t.libs.push("lib", "test")
-  t.test_files = FileList["test/**/test_*.rb"]
-  t.verbose = true
-  t.warning = true
+task :test do
+  ruby("test/run.rb")
 end
 
 task default: [:test]
diff --git a/test/run.rb b/test/run.rb
new file mode 100755
index 0000000..20e41dc
--- /dev/null
+++ b/test/run.rb
@@ -0,0 +1,9 @@
+#!/usr/bin/env ruby
+
+$VERBOSE = true
+
+$LOAD_PATH.unshift("lib", "test")
+
+Dir.glob("test/**/test_*.rb") do |test_rb|
+  require File.expand_path(test_rb)
+end