diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 93622da..1452820 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -32,28 +32,27 @@ jobs:
         run: bundle exec rspec spec
 
   integration_test:
-      runs-on: pub-hk-ubuntu-22.04-xlarge
-      env:
-        STACK: "heroku-22"
-        TEST_VERSION: "3.1.4"
-      steps:
-        - name: Checkout
-          uses: actions/checkout@v3
-        - name: Set up Ruby
-          uses: ruby/setup-ruby@ec02537da5712d66d4d50a0f33b7eb52773b5ed1
-          with:
-            ruby-version: '3.1'
-        - name: Install dependencies
-          run: bundle install
-        - name: Output CHANGELOG
-          run: bundle exec rake "changelog[$TEST_VERSION]"
-        - name: Build Docker image
-          run: bundle exec rake "generate_image[$STACK]"
-        - name: Generate Ruby Dockerfile
-          run: bundle exec rake "new[$TEST_VERSION,$STACK]"
-        - name: Build and package Ruby runtime
-          run: bash "rubies/$STACK/ruby-$TEST_VERSION.sh"
-        - name: Verify ruby executable and output rubygems version
-          run: bundle exec rake "rubygems_version[$TEST_VERSION,$STACK]"
-
-
+    runs-on: pub-hk-ubuntu-22.04-xlarge
+    strategy:
+      matrix:
+        stack: ["heroku-20", "heroku-22"]
+        version: ["3.1.4"]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@ec02537da5712d66d4d50a0f33b7eb52773b5ed1
+        with:
+          ruby-version: '3.1'
+      - name: Install dependencies
+        run: bundle install
+      - name: Output CHANGELOG
+        run: bundle exec rake "changelog[${{matrix.version}}]"
+      - name: Build Docker image
+        run: bundle exec rake "generate_image[${{matrix.stack}}]"
+      - name: Generate Ruby Dockerfile
+        run: bundle exec rake "new[${{matrix.version}},${{matrix.stack}}]"
+      - name: Build and package Ruby runtime
+        run: bash "rubies/${{matrix.stack}}/ruby-${{matrix.version}}.sh"
+      - name: Verify ruby executable and output rubygems version
+        run: bundle exec rake "rubygems_version[${{matrix.version}},${{matrix.stack}}]"
diff --git a/Rakefile b/Rakefile
index 1fbb523..8718663 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,6 +1,7 @@
 $LOAD_PATH.unshift File.expand_path("../lib", __FILE__)
 require "ruby_version"
 require "changelog"
+require "docker_command"
 
 require "fileutils"
 
@@ -35,11 +36,10 @@ end
 
 desc "Output the Rubygems version for a given binary"
 task :rubygems_version, [:version, :stack] do |t, args|
-  stack = args[:stack]
-  ruby_version = args[:version]
-
-  # Extract the binary in a docker image and run `bin/gem -v` to output it's Rubygems version
-  command = "docker run -v $(pwd)/builds/#{stack}:/tmp/output hone/ruby-builder:#{stack} bash -c \"mkdir /tmp/unzipped && tar xzf /tmp/output/ruby-#{ruby_version}.tgz -C /tmp/unzipped && echo 'Rubygems version is: ' && /tmp/unzipped/bin/gem -v\""
+  command = DockerCommand.gem_version_from_tar(
+    stack: args[:stack],
+    ruby_version: RubyVersion.new(args[:version])
+  )
   puts "Running: #{command}"
   pipe(command)
 end
diff --git a/dockerfiles/Dockerfile.heroku-20 b/dockerfiles/Dockerfile.heroku-20
index fc15af7..eb6d251 100644
--- a/dockerfiles/Dockerfile.heroku-20
+++ b/dockerfiles/Dockerfile.heroku-20
@@ -10,4 +10,5 @@ ENV PATH="/root/.cargo/bin:${PATH}"
 # output dir is mounted
 
 ADD build.rb /tmp/build.rb
+COPY lib/ /tmp/lib/
 CMD ["ruby", "/tmp/build.rb", "/tmp/workspace", "/tmp/output", "/tmp/cache"]
diff --git a/lib/docker_command.rb b/lib/docker_command.rb
new file mode 100644
index 0000000..95159ae
--- /dev/null
+++ b/lib/docker_command.rb
@@ -0,0 +1,5 @@
+module DockerCommand
+  def self.gem_version_from_tar(ruby_version:, stack:)
+    "docker run -v $(pwd)/builds/#{stack}:/tmp/output hone/ruby-builder:#{stack} bash -c \"mkdir /tmp/unzipped && tar xzf /tmp/output/#{ruby_version.tar_file_name_output} -C /tmp/unzipped && echo 'Rubygems version is: ' && /tmp/unzipped/bin/gem -v\""
+  end
+end
diff --git a/spec/unit/changelog_spec.rb b/spec/unit/changelog_spec.rb
index de8bc5a..588b4a4 100644
--- a/spec/unit/changelog_spec.rb
+++ b/spec/unit/changelog_spec.rb
@@ -1,7 +1,7 @@
 require "spec_helper"
 require "changelog"
 
-describe RubyVersion do
+describe "Changelog output" do
   it "prints changelog info for regular releases" do
     io = StringIO.new
     Changelog.new(
diff --git a/spec/unit/docker_command_spec.rb b/spec/unit/docker_command_spec.rb
new file mode 100644
index 0000000..aac2818
--- /dev/null
+++ b/spec/unit/docker_command_spec.rb
@@ -0,0 +1,16 @@
+require "spec_helper"
+require "docker_command"
+
+describe DockerCommand do
+  it "Generates docker command for outputting rubygems versions" do
+    actual = DockerCommand.gem_version_from_tar(ruby_version: RubyVersion.new("3.1.4"), stack: "heroku-22")
+    expected = %{docker run -v $(pwd)/builds/heroku-22:/tmp/output hone/ruby-builder:heroku-22 bash -c "mkdir /tmp/unzipped && tar xzf /tmp/output/ruby-3.1.4.tgz -C /tmp/unzipped && echo 'Rubygems version is: ' && /tmp/unzipped/bin/gem -v"}
+    expect(actual).to eq(expected)
+  end
+
+  it "works with preview releases" do
+    actual = DockerCommand.gem_version_from_tar(ruby_version: RubyVersion.new("3.3.0-preview2"), stack: "heroku-22")
+    expected = %{docker run -v $(pwd)/builds/heroku-22:/tmp/output hone/ruby-builder:heroku-22 bash -c "mkdir /tmp/unzipped && tar xzf /tmp/output/ruby-3.3.0.tgz -C /tmp/unzipped && echo 'Rubygems version is: ' && /tmp/unzipped/bin/gem -v"}
+    expect(actual).to eq(expected)
+  end
+end