diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 4ad9d8f..44e75ae 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -19,10 +19,10 @@ jobs:
             composer-deps: lowest
           - php-version: "7.4"
             composer-deps: latest
-          - php-version: "8.0"
-            composer-deps: lowest
           - php-version: "8.0"
             composer-deps: latest
+          - php-version: "8.1"
+            composer-deps: latest
     steps:
       - name: "Checkout"
         uses: "actions/checkout@v2"
@@ -48,10 +48,10 @@ jobs:
           restore-keys: "php-${{ matrix.php-version }}-composer-${{ matrix.composer-deps }}"
 
       - name: "Install dependencies"
-        run: "composer install --no-interaction --no-progress --no-suggest --ignore-platform-reqs"
+        run: "composer install --no-interaction --no-progress --ignore-platform-reqs"
 
       - name: "Update dependencies (lowest)"
-        run: "composer update --no-interaction --no-progress --no-suggest --prefer-lowest --prefer-stable"
+        run: "composer update --no-interaction --no-progress --prefer-lowest --prefer-stable"
         if: ${{ matrix.composer-deps == 'lowest' }}
 
       - name: "Update dependencies (latest)"
diff --git a/composer.json b/composer.json
index ddc0278..959a7d1 100644
--- a/composer.json
+++ b/composer.json
@@ -14,9 +14,9 @@
     }
   ],
   "require": {
-    "php": "^7.4 || ~8.0.0",
-    "cebe/php-openapi": "^1.5.2",
-    "symfony/console": "^v5.1.9"
+    "php": "^7.4 || ~8.0.0 || ~8.1.0",
+    "cebe/php-openapi": "^1.7.0",
+    "symfony/console": "^5.1.9 || ^6.0"
   },
   "require-dev": {
     "doctrine/coding-standard": "^9.0.0",
@@ -59,7 +59,12 @@
     "infection": "infection --threads=4 --coverage=build/coverage"
   },
   "config": {
-    "sort-packages": true
+    "sort-packages": true,
+    "allow-plugins": {
+      "dealerdirect/phpcodesniffer-composer-installer": true,
+      "infection/extension-installer": true,
+      "ocramius/package-versions": true
+    }
   },
   "bin": [
     "bin/openapi-merge"
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 4c07c0d..0cf13e7 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -1,4 +1,4 @@
-FROM php:7.4-cli-alpine
+FROM php:8.0-cli-alpine
 
 RUN php --version
 
diff --git a/tests/Acceptance/ApplicationAcceptanceTest.php b/tests/Acceptance/ApplicationAcceptanceTest.php
index bcaea82..507f867 100644
--- a/tests/Acceptance/ApplicationAcceptanceTest.php
+++ b/tests/Acceptance/ApplicationAcceptanceTest.php
@@ -9,6 +9,9 @@
 use function implode;
 use function shell_exec;
 use function sprintf;
+use function version_compare;
+
+use const PHP_VERSION;
 
 /**
  * @coversNothing
@@ -28,97 +31,12 @@ public function testApplicationRuns(): void
             ])
         ));
 
-        self::assertSame(
-            <<<'EXPECTED_YAML'
-            openapi: 3.0.2
-            info:
-              title: 'Example OpenAPI Definition'
-              description: 'This is the example Description'
-              contact:
-                name: 'Base Author'
-                url: base.example.org
-                email: base-file@example.org
-              license:
-                name: MIT
-                url: 'https://tldrlegal.com/license/mit-license'
-              version: '1.0'
-            servers:
-              -
-                url: 'https://api.base.example.org'
-                description: 'Main Base URL'
-            paths:
-              /ping:
-                get:
-                  tags:
-                    - 'Base Route'
-                  summary: 'Your GET endpoint'
-                  description: 'Description of Ping'
-                  operationId: get-ping
-                  parameters:
-                    -
-                      name: responseWith
-                      in: query
-                      description: 'response with this message'
-                      schema:
-                        maxLength: 20
-                        minLength: 0
-                        type: string
-                  responses:
-                    '200':
-                      description: OK
-                      content:
-                        application/json:
-                          schema:
-                            required:
-                              - response
-                            type: object
-                            properties:
-                              response:
-                                type: string
-                    '400':
-                      description: 'Bad Request'
-                      content:
-                        application/problem+json:
-                          schema:
-                            title: ProblemResponse
-                            required:
-                              - type
-                              - title
-                            type: object
-                            properties:
-                              type:
-                                type: string
-                                description: 'type of the problem'
-                                example: ValidationError
-                              title:
-                                type: string
-                                example: 'Your request parameters didn''t validate.'
-                            description: 'Default Problem Response'
-                post:
-                  summary: 'Your POST endpoint'
-                  description: 'Description of post Ping'
-                  operationId: post-ping
-                  responses:
-                    '200':
-                      description: OK
-                      content:
-                        application/json:
-                          schema:
-                            required:
-                              - response
-                            type: object
-                            properties:
-                              response:
-                                type: string
-            components:
-              schemas: []
-            security: []
-            tags:
-              -
-                name: Base
+        self::assertNotNull($output);
 
-            EXPECTED_YAML,
-            $output
-        );
+        if (version_compare(PHP_VERSION, '8.1.0', '>=')) {
+            self::assertStringEqualsFile(__DIR__ . '/Fixtures/expected_php81.yml', $output);
+        } else {
+            self::assertStringEqualsFile(__DIR__ . '/Fixtures/expected_php80.yml', $output);
+        }
     }
 }
diff --git a/tests/Acceptance/Fixtures/expected_php80.yml b/tests/Acceptance/Fixtures/expected_php80.yml
new file mode 100644
index 0000000..cfca99e
--- /dev/null
+++ b/tests/Acceptance/Fixtures/expected_php80.yml
@@ -0,0 +1,86 @@
+openapi: 3.0.2
+info:
+  title: 'Example OpenAPI Definition'
+  description: 'This is the example Description'
+  contact:
+    name: 'Base Author'
+    url: base.example.org
+    email: base-file@example.org
+  license:
+    name: MIT
+    url: 'https://tldrlegal.com/license/mit-license'
+  version: '1.0'
+servers:
+  -
+    url: 'https://api.base.example.org'
+    description: 'Main Base URL'
+paths:
+  /ping:
+    get:
+      tags:
+        - 'Base Route'
+      summary: 'Your GET endpoint'
+      description: 'Description of Ping'
+      operationId: get-ping
+      parameters:
+        -
+          name: responseWith
+          in: query
+          description: 'response with this message'
+          schema:
+            maxLength: 20
+            minLength: 0
+            type: string
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                required:
+                  - response
+                type: object
+                properties:
+                  response:
+                    type: string
+        '400':
+          description: 'Bad Request'
+          content:
+            application/problem+json:
+              schema:
+                title: ProblemResponse
+                required:
+                  - type
+                  - title
+                type: object
+                properties:
+                  type:
+                    type: string
+                    description: 'type of the problem'
+                    example: ValidationError
+                  title:
+                    type: string
+                    example: 'Your request parameters didn''t validate.'
+                description: 'Default Problem Response'
+    post:
+      summary: 'Your POST endpoint'
+      description: 'Description of post Ping'
+      operationId: post-ping
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                required:
+                  - response
+                type: object
+                properties:
+                  response:
+                    type: string
+components:
+  schemas: {  }
+security: []
+tags:
+  -
+    name: Base
diff --git a/tests/Acceptance/Fixtures/expected_php81.yml b/tests/Acceptance/Fixtures/expected_php81.yml
new file mode 100644
index 0000000..3896b30
--- /dev/null
+++ b/tests/Acceptance/Fixtures/expected_php81.yml
@@ -0,0 +1,86 @@
+openapi: 3.0.2
+info:
+  title: 'Example OpenAPI Definition'
+  description: 'This is the example Description'
+  contact:
+    name: 'Base Author'
+    url: base.example.org
+    email: base-file@example.org
+  license:
+    name: MIT
+    url: 'https://tldrlegal.com/license/mit-license'
+  version: '1.0'
+servers:
+  -
+    url: 'https://api.base.example.org'
+    description: 'Main Base URL'
+paths:
+  /ping:
+    get:
+      tags:
+        - 'Base Route'
+      summary: 'Your GET endpoint'
+      description: 'Description of Ping'
+      operationId: get-ping
+      parameters:
+        -
+          name: responseWith
+          in: query
+          description: 'response with this message'
+          schema:
+            maxLength: 20
+            minLength: 0
+            type: string
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                required:
+                  - response
+                type: object
+                properties:
+                  response:
+                    type: string
+        '400':
+          description: 'Bad Request'
+          content:
+            application/problem+json:
+              schema:
+                title: ProblemResponse
+                required:
+                  - type
+                  - title
+                type: object
+                properties:
+                  type:
+                    type: string
+                    description: 'type of the problem'
+                    example: ValidationError
+                  title:
+                    type: string
+                    example: "Your request parameters didn't validate."
+                description: 'Default Problem Response'
+    post:
+      summary: 'Your POST endpoint'
+      description: 'Description of post Ping'
+      operationId: post-ping
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                required:
+                  - response
+                type: object
+                properties:
+                  response:
+                    type: string
+components:
+  schemas: {  }
+security: []
+tags:
+  -
+    name: Base