diff --git a/Makefile b/Makefile
index acfca9e2..0d7ca4cf 100644
--- a/Makefile
+++ b/Makefile
@@ -37,6 +37,12 @@ fix-style: php-cs-fixer.phar
 	$(DOCKER_PHP) vendor/bin/indent --spaces .php_cs.dist
 	$(DOCKER_PHP) ./php-cs-fixer.phar fix src/ --diff
 
+cli:
+	docker-compose run --rm php bash
+
+#cli_root:
+#	docker-compose exec --user="root" php bash
+
 install:
 	$(DOCKER_PHP) composer install --prefer-dist --no-interaction --no-progress --ansi
 	$(DOCKER_NODE) yarn install
diff --git a/composer.json b/composer.json
index a3054a52..7bbadcae 100644
--- a/composer.json
+++ b/composer.json
@@ -20,7 +20,7 @@
 	"require": {
 		"php": ">=7.1.0",
 		"ext-json": "*",
-		"symfony/yaml": "^3.4 || ^4 || ^5 || ^6 || ^7.0",
+		"ext-yaml": "*",
 		"justinrainbow/json-schema": "^5.2"
 	},
 	"require-dev": {
@@ -28,8 +28,6 @@
 		"phpunit/phpunit": "^6.5 || ^7.5 || ^8.5 || ^9.4",
 		"oai/openapi-specification": "3.0.3",
 		"mermade/openapi3-examples": "1.0.0",
-		"apis-guru/openapi-directory": "1.0.0",
-		"nexmo/api-specification": "1.0.0",
 		"phpstan/phpstan": "^0.12.0"
 	},
 	"conflict": {
diff --git a/src/Reader.php b/src/Reader.php
index 99ee5c36..c229fe07 100644
--- a/src/Reader.php
+++ b/src/Reader.php
@@ -13,7 +13,6 @@
 use cebe\openapi\json\InvalidJsonPointerSyntaxException;
 use cebe\openapi\json\JsonPointer;
 use cebe\openapi\spec\OpenApi;
-use Symfony\Component\Yaml\Yaml;
 
 /**
  * Utility class to simplify reading JSON or YAML OpenAPI specs.
@@ -54,7 +53,7 @@ public static function readFromJson(string $json, string $baseType = OpenApi::cl
      */
     public static function readFromYaml(string $yaml, string $baseType = OpenApi::class): SpecObjectInterface
     {
-        return new $baseType(Yaml::parse($yaml));
+        return new $baseType(yaml_parse($yaml));
     }
 
     /**
diff --git a/src/ReferenceContext.php b/src/ReferenceContext.php
index bde0a964..e5233539 100644
--- a/src/ReferenceContext.php
+++ b/src/ReferenceContext.php
@@ -11,7 +11,6 @@
 use cebe\openapi\exceptions\UnresolvableReferenceException;
 use cebe\openapi\json\JsonPointer;
 use cebe\openapi\spec\Reference;
-use Symfony\Component\Yaml\Yaml;
 
 /**
  * ReferenceContext represents a context in which references are resolved.
@@ -224,7 +223,7 @@ public function fetchReferencedFile($uri)
         if (strpos(ltrim($content), '{') === 0) {
             $parsedContent = json_decode($content, true);
         } else {
-            $parsedContent = Yaml::parse($content);
+            $parsedContent = yaml_parse($content);
         }
         $this->_cache->set('FILE_CONTENT://' . $uri, 'FILE_CONTENT', $parsedContent);
         return $parsedContent;
diff --git a/src/Writer.php b/src/Writer.php
index faa08f46..030ba267 100644
--- a/src/Writer.php
+++ b/src/Writer.php
@@ -9,7 +9,6 @@
 
 use cebe\openapi\exceptions\IOException;
 use cebe\openapi\spec\OpenApi;
-use Symfony\Component\Yaml\Yaml;
 
 /**
  * Utility class to simplify writing JSON or YAML OpenAPI specs.
@@ -35,7 +34,10 @@ public static function writeToJson(SpecObjectInterface $object, int $flags = JSO
      */
     public static function writeToYaml(SpecObjectInterface $object): string
     {
-        return Yaml::dump($object->getSerializableData(), 256, 2, Yaml::DUMP_OBJECT_AS_MAP | Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE);
+//        return Yaml::dump($object->getSerializableData(), 256, 2, Yaml::DUMP_OBJECT_AS_MAP | Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE);
+        return yaml_emit(
+            json_decode(json_encode($object->getSerializableData()), true)
+        );
     }
 
     /**
diff --git a/src/spec/Reference.php b/src/spec/Reference.php
index cda612a9..7b37b0d8 100644
--- a/src/spec/Reference.php
+++ b/src/spec/Reference.php
@@ -8,7 +8,6 @@
 namespace cebe\openapi\spec;
 
 use cebe\openapi\DocumentContextInterface;
-use cebe\openapi\exceptions\IOException;
 use cebe\openapi\exceptions\TypeErrorException;
 use cebe\openapi\exceptions\UnresolvableReferenceException;
 use cebe\openapi\json\InvalidJsonPointerSyntaxException;
@@ -17,7 +16,6 @@
 use cebe\openapi\json\NonexistentJsonPointerReferenceException;
 use cebe\openapi\ReferenceContext;
 use cebe\openapi\SpecObjectInterface;
-use Symfony\Component\Yaml\Yaml;
 
 /**
  * Reference Object
diff --git a/tests/WriterTest.php b/tests/WriterTest.php
index fc415b51..7a9f4f78 100644
--- a/tests/WriterTest.php
+++ b/tests/WriterTest.php
@@ -74,11 +74,13 @@ public function testWriteYaml()
 
 
         $this->assertEquals(preg_replace('~\R~', "\n", <<<YAML
+---
 openapi: 3.0.0
 info:
-  title: 'Test API'
+  title: Test API
   version: 1.0.0
-paths: {  }
+paths: []
+...
 
 YAML
         ),
@@ -121,12 +123,14 @@ public function testWriteEmptySecurityYaml()
 
 
         $this->assertEquals(preg_replace('~\R~', "\n", <<<YAML
+---
 openapi: 3.0.0
 info:
-  title: 'Test API'
+  title: Test API
   version: 1.0.0
-paths: {  }
+paths: []
 security: []
+...
 
 YAML
         ),
@@ -173,14 +177,15 @@ public function testWriteEmptySecurityPartYaml()
 
 
         $this->assertEquals(preg_replace('~\R~', "\n", <<<YAML
+---
 openapi: 3.0.0
 info:
-  title: 'Test API'
+  title: Test API
   version: 1.0.0
-paths: {  }
+paths: []
 security:
-  -
-    Bearer: []
+- Bearer: []
+...
 
 YAML
         ),
diff --git a/tests/docker/Dockerfile b/tests/docker/Dockerfile
index 4dce3b53..95d01c69 100644
--- a/tests/docker/Dockerfile
+++ b/tests/docker/Dockerfile
@@ -19,11 +19,14 @@ RUN apt-get update && \
             curl \
             libcurl4-openssl-dev \
             libssl-dev \
+            libyaml-dev \
         --no-install-recommends && \
         apt-get clean && \
         rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* \
         && pecl install xdebug-2.9.6 \
+        && pecl install yaml \
         && docker-php-ext-enable xdebug \
+        && docker-php-ext-enable yaml \
         && docker-php-ext-install \
                 zip \
                 curl \
diff --git a/tests/spec/MediaTypeTest.php b/tests/spec/MediaTypeTest.php
index 125e721d..46aeb0b6 100644
--- a/tests/spec/MediaTypeTest.php
+++ b/tests/spec/MediaTypeTest.php
@@ -1,8 +1,8 @@
 <?php
 
 use cebe\openapi\Reader;
-use cebe\openapi\spec\MediaType;
 use cebe\openapi\spec\Example;
+use cebe\openapi\spec\MediaType;
 use cebe\openapi\spec\OpenApi;
 use cebe\openapi\spec\Reference;
 use Symfony\Component\Yaml\Yaml;
@@ -125,7 +125,7 @@ public function testPathsCanNotBeCreatedFromBullshit($config, $expectedException
 
     public function testUnresolvedReferencesInEncoding()
     {
-        $yaml = Yaml::parse(<<<'YAML'
+        $yaml = yaml_parse(<<<'YAML'
 openapi: "3.0.0"
 info:
   version: 1.0.0
diff --git a/tests/spec/OpenApiTest.php b/tests/spec/OpenApiTest.php
index 20b568ed..d9b32981 100644
--- a/tests/spec/OpenApiTest.php
+++ b/tests/spec/OpenApiTest.php
@@ -30,7 +30,7 @@ public function testReadPetStore()
     {
         $openApiFile = __DIR__ . '/../../vendor/oai/openapi-specification/examples/v3.0/petstore.yaml';
 
-        $yaml = Yaml::parse(file_get_contents($openApiFile));
+        $yaml = yaml_parse(file_get_contents($openApiFile));
         $openapi = new OpenApi($yaml);
 
         $result = $openapi->validate();
diff --git a/tests/spec/ReferenceTest.php b/tests/spec/ReferenceTest.php
index b94c946e..a7983d00 100644
--- a/tests/spec/ReferenceTest.php
+++ b/tests/spec/ReferenceTest.php
@@ -1,13 +1,13 @@
 <?php
 
 use cebe\openapi\Reader;
+use cebe\openapi\spec\Example;
 use cebe\openapi\spec\OpenApi;
 use cebe\openapi\spec\Parameter;
 use cebe\openapi\spec\Reference;
 use cebe\openapi\spec\RequestBody;
 use cebe\openapi\spec\Response;
 use cebe\openapi\spec\Schema;
-use cebe\openapi\spec\Example;
 
 /**
  * @covers \cebe\openapi\spec\Reference
@@ -441,21 +441,23 @@ public function testTransitiveReferenceOverTwoFiles()
         $yaml = \cebe\openapi\Writer::writeToYaml($openapi);
 
         $expected = <<<YAML
+---
 openapi: 3.0.0
 info:
-  title: 'Ref Example'
+  title: Ref Example
   version: 1.0.0
 paths:
   /pet:
     get:
       responses:
-        '200':
-          description: 'return a pet'
+        200:
+          description: return a pet
   /cat:
     get:
       responses:
-        '200':
-          description: 'return a cat'
+        200:
+          description: return a cat
+...
 
 YAML;
         // remove line endings to make string equal on windows
@@ -474,53 +476,53 @@ public function testReferencedCommonParamsInReferencedPath()
         $openapi = Reader::readFromYamlFile(__DIR__ . '/data/reference/ReferencedCommonParamsInReferencedPath.yml', OpenApi::class, \cebe\openapi\ReferenceContext::RESOLVE_MODE_INLINE);
         $yaml = \cebe\openapi\Writer::writeToYaml($openapi);
         $expected = <<<YAML
+---
 openapi: 3.0.0
 info:
-  title: 'Nested reference with common path params'
+  title: Nested reference with common path params
   version: 1.0.0
 paths:
   /example:
     get:
       responses:
-        '200':
-          description: 'OK if common params can be references'
+        200:
+          description: OK if common params can be references
       request:
         content:
           application/json:
             examples:
               user:
-                summary: 'User Example'
+                summary: User Example
                 externalValue: ./paths/examples/user-example.json
               userex:
-                summary: 'External User Example'
-                externalValue: 'https://api.example.com/examples/user-example.json'
+                summary: External User Example
+                externalValue: https://api.example.com/examples/user-example.json
     parameters:
-      -
-        name: test
-        in: header
-        description: 'Test parameter to be referenced'
-        required: true
-        schema:
-          enum:
-            - test
-          type: string
+    - name: test
+      in: header
+      description: Test parameter to be referenced
+      required: true
+      schema:
+        enum:
+        - test
+        type: string
     x-something: something
   /something:
     get:
       responses:
-        '200':
-          description: 'OK if common params can be references'
+        200:
+          description: OK if common params can be references
     parameters:
-      -
-        name: test
-        in: header
-        description: 'Test parameter to be referenced'
-        required: true
-        schema:
-          enum:
-            - test
-          type: string
+    - name: test
+      in: header
+      description: Test parameter to be referenced
+      required: true
+      schema:
+        enum:
+        - test
+        type: string
     x-something: something
+...
 
 YAML;
         // remove line endings to make string equal on windows
@@ -541,16 +543,17 @@ public function testResolveRelativePathInline()
         $yaml = \cebe\openapi\Writer::writeToYaml($openapi);
 
         $expected = <<<YAML
+---
 openapi: 3.0.3
 info:
-  title: 'Link Example'
+  title: Link Example
   version: 1.0.0
 paths:
   /pet:
     get:
       responses:
-        '200':
-          description: 'return a pet'
+        200:
+          description: return a pet
 components:
   schemas:
     Pet:
@@ -561,7 +564,7 @@ public function testResolveRelativePathInline()
           format: int64
         cat:
           \$ref: '#/components/schemas/Cat'
-      description: 'A Pet'
+      description: A Pet
     Cat:
       type: object
       properties:
@@ -570,10 +573,11 @@ public function testResolveRelativePathInline()
           format: int64
         name:
           type: string
-          description: 'the cats name'
+          description: the cats name
         pet:
           \$ref: '#/components/schemas/Pet'
-      description: 'A Cat'
+      description: A Cat
+...
 
 YAML;
         // remove line endings to make string equal on windows
@@ -594,16 +598,17 @@ public function testResolveRelativePathAll()
         $yaml = \cebe\openapi\Writer::writeToYaml($openapi);
 
         $expected = <<<YAML
+---
 openapi: 3.0.3
 info:
-  title: 'Link Example'
+  title: Link Example
   version: 1.0.0
 paths:
   /pet:
     get:
       responses:
-        '200':
-          description: 'return a pet'
+        200:
+          description: return a pet
 components:
   schemas:
     Pet:
@@ -620,11 +625,11 @@ public function testResolveRelativePathAll()
               format: int64
             name:
               type: string
-              description: 'the cats name'
+              description: the cats name
             pet:
               \$ref: '#/components/schemas/Pet'
-          description: 'A Cat'
-      description: 'A Pet'
+          description: A Cat
+      description: A Pet
     Cat:
       type: object
       properties:
@@ -633,7 +638,7 @@ public function testResolveRelativePathAll()
           format: int64
         name:
           type: string
-          description: 'the cats name'
+          description: the cats name
         pet:
           type: object
           properties:
@@ -642,8 +647,9 @@ public function testResolveRelativePathAll()
               format: int64
             cat:
               \$ref: '#/components/schemas/Cat'
-          description: 'A Pet'
-      description: 'A Cat'
+          description: A Pet
+      description: A Cat
+...
 
 YAML;
         // remove line endings to make string equal on windows