diff --git a/.build/not-required/composer.json b/.build/not-required/composer.json
new file mode 100644
index 0000000..139bf32
--- /dev/null
+++ b/.build/not-required/composer.json
@@ -0,0 +1,24 @@
+{
+  "name": "ergebnis/composer-normalize-action",
+  "type": "library",
+  "description": "Provides a GitHub action for running ergebnis/composer-normalize.",
+  "homepage": "https://github.com/ergebnis/composer-normalize-action",
+  "license": "MIT",
+  "authors": [
+    {
+      "name": "Andreas Möller",
+      "email": "am@localheinz.com"
+    }
+  ],
+  "require": {
+    "php": "^7.3"
+  },
+  "config": {
+    "preferred-install": "dist",
+    "sort-packages": true
+  },
+  "support": {
+    "issues": "https://github.com/ergebnis/composer-normalize-action/issues",
+    "source": "https://github.com/ergebnis/composer-normalize-action"
+  }
+}
diff --git a/.build/not-required/composer.lock b/.build/not-required/composer.lock
new file mode 100644
index 0000000..1b9c5e3
--- /dev/null
+++ b/.build/not-required/composer.lock
@@ -0,0 +1,19 @@
+{
+    "_readme": [
+        "This file locks the dependencies of your project to a known state",
+        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
+        "This file is @generated automatically"
+    ],
+    "content-hash": "fab88dc8bd4860f2943141b6c195b9ba",
+    "packages": [],
+    "packages-dev": [],
+    "aliases": [],
+    "minimum-stability": "stable",
+    "stability-flags": [],
+    "prefer-stable": false,
+    "prefer-lowest": false,
+    "platform": {
+        "php": "^7.3"
+    },
+    "platform-dev": []
+}
diff --git a/.build/composer.json b/.build/required/composer.json
similarity index 100%
rename from .build/composer.json
rename to .build/required/composer.json
diff --git a/.build/composer.lock b/.build/required/composer.lock
similarity index 100%
rename from .build/composer.lock
rename to .build/required/composer.lock
diff --git a/.github/settings.yml b/.github/settings.yml
index 7c10cb7..ad19a91 100644
--- a/.github/settings.yml
+++ b/.github/settings.yml
@@ -14,10 +14,10 @@ branches:
         required_approving_review_count: 1
       required_status_checks:
         contexts:
-          - "Docker image (no)"
-          - "Docker image (yes)"
-          - "GitHub Action (no)"
-          - "GitHub Action (yes)"
+          - "Docker image (not-required)"
+          - "Docker image (required)"
+          - "GitHub Action (not-required)"
+          - "GitHub Action (required)"
         strict: false
       restrictions: null
 
diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index a6c52e6..3bb9a6d 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -11,6 +11,12 @@ jobs:
 
     runs-on: "ubuntu-latest"
 
+    strategy:
+      matrix:
+        required:
+          - "not-required"
+          - "required"
+
     env:
       DOCKER_IMAGE: "ergebnis/composer-normalize-action"
 
@@ -22,19 +28,25 @@ jobs:
         run: "docker build --tag ${DOCKER_IMAGE}:latest ."
 
       - name: "Run Docker image with default behaviour"
-        run: "docker run --interactive --rm --workdir=/app --volume ${GITHUB_WORKSPACE}/.build:/app ${{ env.DOCKER_IMAGE }}:latest"
+        run: "docker run --interactive --rm --workdir=/app --volume ${GITHUB_WORKSPACE}/.build/${{ matrix.required }}:/app ${{ env.DOCKER_IMAGE }}:latest"
 
       - name: "Run Docker image with custom behaviour, specifying options"
-        run: "docker run --interactive --rm --workdir=/app --volume ${GITHUB_WORKSPACE}/.build:/app ${{ env.DOCKER_IMAGE }}:latest --diff --indent-size=1 --indent-style=space --no-update-lock"
+        run: "docker run --interactive --rm --workdir=/app --volume ${GITHUB_WORKSPACE}/.build/${{ matrix.required }}:/app ${{ env.DOCKER_IMAGE }}:latest --diff --indent-size=1 --indent-style=space --no-update-lock"
 
       - name: "Run Docker image with custom behaviour, specifying argument and options"
-        run: "docker run --interactive --rm --workdir=/app --volume ${GITHUB_WORKSPACE}:/app ${{ env.DOCKER_IMAGE }}:latest .build/composer.json --diff --indent-size=2 --indent-style=space  --no-update-lock"
+        run: "docker run --interactive --rm --workdir=/app --volume ${GITHUB_WORKSPACE}:/app ${{ env.DOCKER_IMAGE }}:latest .build/${{ matrix.required }}/composer.json --diff --indent-size=2 --indent-style=space  --no-update-lock"
 
   github-action:
     name: "GitHub Action"
 
     runs-on: "ubuntu-latest"
 
+    strategy:
+      matrix:
+        required:
+          - "not-required"
+          - "required"
+
     env:
       DOCKER_IMAGE: "ergebnis/composer-normalize-action"
 
@@ -42,8 +54,8 @@ jobs:
       - name: "Checkout"
         uses: "actions/checkout@v2.0.0"
 
-      - name: "Copy composer.json from .build into root directory"
-        run: "cp .build/composer.json composer.json"
+      - name: "Copy composer.json from .build/${{ matrix.required }} into root directory"
+        run: "cp .build/${{ matrix.required }}/composer.json composer.json"
 
       - name: "Run GitHub Action with default behavior"
         uses: "./"
@@ -59,4 +71,4 @@ jobs:
       - name: "Run GitHub Action with custom behavior, specifying argument and options"
         uses: "./"
         with:
-          args: ".build/composer.json --diff --indent-size=1 --indent-style=tab --no-update-lock"
+          args: ".build/${{ matrix.required }}/composer.json --diff --indent-size=1 --indent-style=tab --no-update-lock"
diff --git a/.gitignore b/.gitignore
index 57872d0..48b8bf9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1 @@
-/vendor/
+vendor/
diff --git a/Makefile b/Makefile
index 80cccee..b00c8ac 100644
--- a/Makefile
+++ b/Makefile
@@ -7,11 +7,14 @@ it: docker ## Runs the docker target
 docker: ## Builds, tags, and runs the Docker image
 	docker build --tag ${DOCKER_IMAGE} .
     # Run Docker image with default behaviour
-	docker run --interactive --rm --tty --workdir=/app --volume ${PWD}/.build:/app ${DOCKER_IMAGE}:latest
+	docker run --interactive --rm --tty --workdir=/app --volume ${PWD}/.build/not-required:/app ${DOCKER_IMAGE}:latest
+	docker run --interactive --rm --tty --workdir=/app --volume ${PWD}/.build/required:/app ${DOCKER_IMAGE}:latest
 	# Run Docker image with custom behaviour, specifying options
-	docker run --interactive --rm --tty --workdir=/app --volume ${PWD}/.build:/app ${DOCKER_IMAGE}:latest --diff --indent-size=1 --indent-style=space --no-update-lock
+	docker run --interactive --rm --tty --workdir=/app --volume ${PWD}/.build/not-required:/app ${DOCKER_IMAGE}:latest --diff --indent-size=1 --indent-style=space --no-update-lock
+	docker run --interactive --rm --tty --workdir=/app --volume ${PWD}/.build/required:/app ${DOCKER_IMAGE}:latest --diff --indent-size=1 --indent-style=space --no-update-lock
 	# Run Docker image with custom behaviour, specifying argument and options
-	docker run --interactive --rm --tty --workdir=/app --volume ${PWD}:/app ${DOCKER_IMAGE}:latest .build/composer.json --diff --indent-size=2 --indent-style=space  --no-update-lock
+	docker run --interactive --rm --tty --workdir=/app --volume ${PWD}:/app ${DOCKER_IMAGE}:latest .build/not-required/composer.json --diff --indent-size=2 --indent-style=space  --no-update-lock
+	docker run --interactive --rm --tty --workdir=/app --volume ${PWD}:/app ${DOCKER_IMAGE}:latest .build/required/composer.json --diff --indent-size=2 --indent-style=space  --no-update-lock
 
 help: ## Displays this list of targets with descriptions
 	@grep -E '^[a-zA-Z0-9_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[32m%-30s\033[0m %s\n", $$1, $$2}'