diff --git a/DependencyInjection/Configuration.php b/DependencyInjection/Configuration.php
index 2eb1441..5356c53 100644
--- a/DependencyInjection/Configuration.php
+++ b/DependencyInjection/Configuration.php
@@ -22,7 +22,6 @@ final class Configuration implements ConfigurationInterface
         $treeBuilder
             ->root('nelmio_api_doc')
             ->children()
-                ->scalarNode('source_folder')->defaultValue('%kernel.root_dir%/../src')->end()
                 ->arrayNode('routes')
                     ->info('Filter the routes that are documented')
                     ->addDefaultsIfNotSet()
diff --git a/DependencyInjection/NelmioApiDocExtension.php b/DependencyInjection/NelmioApiDocExtension.php
index 458d8bd..829df1d 100644
--- a/DependencyInjection/NelmioApiDocExtension.php
+++ b/DependencyInjection/NelmioApiDocExtension.php
@@ -45,15 +45,10 @@ final class NelmioApiDocExtension extends Extension implements PrependExtensionI
         $routeCollectionBuilder->replaceArgument(0, $config['routes']['path_patterns']);
 
         // Import services needed for each library
+        $loader->load('swagger_php.xml');
         if (class_exists(DocBlockFactory::class)) {
             $loader->load('php_doc.xml');
         }
-        if (class_exists(Swagger::class)) {
-            $loader->load('swagger_php.xml');
-
-            $swaggerPHPDescriber = $container->getDefinition('nelmio_api_doc.describers.swagger_php');
-            $swaggerPHPDescriber->replaceArgument(0, $config['source_folder']);
-        }
         if (interface_exists(ParamInterface::class)) {
             $loader->load('fos_rest.xml');
         }
diff --git a/Describer/SwaggerPhpDescriber.php b/Describer/SwaggerPhpDescriber.php
index 5f26d1c..d016b94 100644
--- a/Describer/SwaggerPhpDescriber.php
+++ b/Describer/SwaggerPhpDescriber.php
@@ -14,37 +14,59 @@ namespace Nelmio\ApiDocBundle\Describer;
 use Nelmio\ApiDocBundle\SwaggerPhp\AddDefaults;
 use Nelmio\ApiDocBundle\SwaggerPhp\ModelRegister;
 use Nelmio\ApiDocBundle\SwaggerPhp\OperationResolver;
+use Nelmio\ApiDocBundle\Util\ControllerReflector;
 use Swagger\Analyser;
 use Swagger\Analysis;
+use Symfony\Component\Finder\Finder;
+use Symfony\Component\Routing\RouteCollection;
 
 final class SwaggerPhpDescriber extends ExternalDocDescriber implements ModelRegistryAwareInterface
 {
     use ModelRegistryAwareTrait;
 
-    private $operationResolver;
+    private $routeCollection;
+    private $controllerReflector;
 
-    public function __construct(string $projectPath, bool $overwrite = false)
+    public function __construct(RouteCollection $routeCollection, ControllerReflector $controllerReflector, bool $overwrite = false)
     {
-        $nelmioNamespace = 'Nelmio\\ApiDocBundle\\';
-        if (!in_array($nelmioNamespace, Analyser::$whitelist)) {
-            Analyser::$whitelist[] = $nelmioNamespace;
-        }
+        $this->routeCollection = $routeCollection;
+        $this->controllerReflector = $controllerReflector;
 
-        parent::__construct(function () use ($projectPath) {
-            $options = ['processors' => $this->getProcessors()];
-            $annotation = \Swagger\scan($projectPath, $options);
+        parent::__construct(function () {
+            $whitelist = Analyser::$whitelist;
+            Analyser::$whitelist = false;
+            try {
+                $options = ['processors' => $this->getProcessors()];
+                $annotation = \Swagger\scan($this->getFinder(), $options);
 
-            return json_decode(json_encode($annotation));
+                return json_decode(json_encode($annotation));
+            } finally {
+                Analyser::$whitelist = $whitelist;
+            }
         }, $overwrite);
     }
 
-    /**
-     * If set, the describer will try to complete paths and create
-     * implicit operations.
-     */
-    public function setOperationResolver(OperationResolver $operationResolver)
+    private function getFinder()
     {
-        $this->operationResolver = $operationResolver;
+        $files = [];
+        foreach ($this->routeCollection->all() as $route) {
+            if (!$route->hasDefault('_controller')) {
+                continue;
+            }
+
+            // if able to resolve the controller
+            $controller = $route->getDefault('_controller');
+            if ($callable = $this->controllerReflector->getReflectionClassAndMethod($controller)) {
+                list($class, $method) = $callable;
+
+                $files[$class->getFileName()] = true;
+            }
+        }
+
+        $finder = new Finder();
+        $finder->append(array_keys($files));
+
+        return $finder;
     }
 
     private function getProcessors(): array
@@ -52,10 +74,8 @@ final class SwaggerPhpDescriber extends ExternalDocDescriber implements ModelReg
         $processors = [
             new AddDefaults(),
             new ModelRegister($this->modelRegistry),
+            new OperationResolver($this->routeCollection, $this->controllerReflector),
         ];
-        if (null !== $this->operationResolver) {
-            $processors[] = $this->operationResolver;
-        }
 
         return array_merge($processors, Analysis::processors());
     }
diff --git a/ModelDescriber/ScalarModelDescriber.php b/ModelDescriber/ScalarModelDescriber.php
index 4581dcf..48a502f 100644
--- a/ModelDescriber/ScalarModelDescriber.php
+++ b/ModelDescriber/ScalarModelDescriber.php
@@ -21,7 +21,7 @@ class ScalarModelDescriber implements ModelDescriberInterface
         Type::BUILTIN_TYPE_INT => 'integer',
         Type::BUILTIN_TYPE_FLOAT => 'float',
         Type::BUILTIN_TYPE_STRING => 'string',
-        Type::BUILTIN_TYPE_BOOL => 'boolean'
+        Type::BUILTIN_TYPE_BOOL => 'boolean',
     ];
 
     public function describe(Model $model, Schema $schema)
diff --git a/Resources/config/swagger_php.xml b/Resources/config/swagger_php.xml
index e582117..70bf245 100644
--- a/Resources/config/swagger_php.xml
+++ b/Resources/config/swagger_php.xml
@@ -5,31 +5,15 @@
 
     <services>
         <service id="nelmio_api_doc.describers.swagger_php" class="Nelmio\ApiDocBundle\Describer\SwaggerPhpDescriber" public="false">
-            <argument>%kernel.root_dir%</argument>
-            <call method="setOperationResolver">
-              <argument type="service" id="nelmio_api_doc.describers.swagger_php.operation_resolver" />
-            </call>
+            <argument type="service">
+                <service class="Symfony\Component\Routing\RouteCollection">
+                    <factory service="router" method="getRouteCollection" />
+                </service>
+            </argument>
+            <argument type="service" id="nelmio_api_doc.controller_reflector" />
 
             <tag name="nelmio_api_doc.describer" priority="-200" />
         </service>
-
-        <service id="nelmio_api_doc.describers.swagger_php.path_resolver" class="Nelmio\ApiDocBundle\SwaggerPhp\PathResolver" public="false">
-            <argument type="service">
-                <service class="Symfony\Component\Routing\RouteCollection">
-                    <factory service="router" method="getRouteCollection" />
-                </service>
-            </argument>
-            <argument type="service" id="nelmio_api_doc.controller_reflector" />
-        </service>
-
-        <service id="nelmio_api_doc.describers.swagger_php.operation_resolver" class="Nelmio\ApiDocBundle\SwaggerPhp\OperationResolver" public="false">
-            <argument type="service">
-                <service class="Symfony\Component\Routing\RouteCollection">
-                    <factory service="router" method="getRouteCollection" />
-                </service>
-            </argument>
-            <argument type="service" id="nelmio_api_doc.controller_reflector" />
-        </service>
     </services>
 
 </container>
diff --git a/Tests/Describer/SwaggerPhpDescriberTest.php b/Tests/Describer/SwaggerPhpDescriberTest.php
deleted file mode 100644
index 0102f2e..0000000
--- a/Tests/Describer/SwaggerPhpDescriberTest.php
+++ /dev/null
@@ -1,34 +0,0 @@
-<?php
-
-/*
- * This file is part of the NelmioApiDocBundle package.
- *
- * (c) Nelmio
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace Nelmio\ApiDocBundle\Tests\Describer;
-
-use EXSyst\Component\Swagger\Swagger;
-use Nelmio\ApiDocBundle\Describer\SwaggerPhpDescriber;
-use Nelmio\ApiDocBundle\Model\ModelRegistry;
-
-class SwaggerPhpDescriberTest extends AbstractDescriberTest
-{
-    public function testDescribe()
-    {
-        $api = $this->getSwaggerDoc();
-        $info = $api->getInfo();
-
-        $this->assertEquals('My Awesome App', $info->getTitle());
-        $this->assertEquals('1.3', $info->getVersion());
-    }
-
-    protected function setUp()
-    {
-        $this->describer = new SwaggerPhpDescriber(__DIR__.'/../Fixtures');
-        $this->describer->setModelRegistry(new ModelRegistry([], new Swagger()));
-    }
-}
diff --git a/Tests/Fixtures/SwaggerPhp/Api.php b/Tests/Fixtures/SwaggerPhp/Api.php
deleted file mode 100644
index b1b8efb..0000000
--- a/Tests/Fixtures/SwaggerPhp/Api.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-/*
- * This file is part of the NelmioApiDocBundle package.
- *
- * (c) Nelmio
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace Nelmio\ApiDocBundle\Tests\Functional\Fixtures\SwaggerPhp;
-
-use Swagger\Annotations\Info;
-
-/**
- * @Info(
- *   title="My Awesome App",
- *   version="1.3"
- * )
- */
-class Api
-{
-}
diff --git a/Tests/Functional/Controller/ApiController.php b/Tests/Functional/Controller/ApiController.php
index f8c62d6..3fa6f75 100644
--- a/Tests/Functional/Controller/ApiController.php
+++ b/Tests/Functional/Controller/ApiController.php
@@ -13,9 +13,7 @@ namespace Nelmio\ApiDocBundle\Tests\Functional\Controller;
 
 use FOS\RestBundle\Controller\Annotations\QueryParam;
 use FOS\RestBundle\Controller\Annotations\RequestParam;
-use Nelmio\ApiDocBundle\Annotation\ApiDoc;
 use Nelmio\ApiDocBundle\Annotation\Model;
-use Nelmio\ApiDocBundle\Tests\Functional\Entity\Dummy;
 use Nelmio\ApiDocBundle\Tests\Functional\Entity\User;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
 use Swagger\Annotations as SWG;
@@ -41,7 +39,7 @@ class ApiController
      * @SWG\Response(
      *     response="201",
      *     description="Operation automatically detected",
-     *     @Model(type="Nelmio\ApiDocBundle\Tests\Functional\Entity\User")
+     *     @Model(type=User::class)
      * )
      * @SWG\Parameter(
      *     name="foo",
@@ -49,7 +47,7 @@ class ApiController
      *     description="This is a parameter",
      *     @SWG\Schema(
      *         type="array",
-     *         @Model(type="Nelmio\ApiDocBundle\Tests\Functional\Entity\User")
+     *         @Model(type=User::class)
      *     )
      * )
      */
diff --git a/Tests/Functional/TestKernel.php b/Tests/Functional/TestKernel.php
index 4c93ec2..9cf59d5 100644
--- a/Tests/Functional/TestKernel.php
+++ b/Tests/Functional/TestKernel.php
@@ -62,7 +62,6 @@ class TestKernel extends Kernel
 
         // Filter routes
         $c->loadFromExtension('nelmio_api_doc', [
-            'source_folder' => '%kernel.root_dir%',
             'routes' => [
                 'path_patterns' => ['^/api(?!/admin)'],
             ],
diff --git a/Util/ControllerReflector.php b/Util/ControllerReflector.php
index a4b7d0f..6a6f9ff 100644
--- a/Util/ControllerReflector.php
+++ b/Util/ControllerReflector.php
@@ -22,6 +22,8 @@ final class ControllerReflector
     private $container;
     private $controllerNameParser;
 
+    private $controllers = [];
+
     public function __construct(ContainerInterface $container, ControllerNameParser $controllerNameParser)
     {
         $this->container = $container;
@@ -69,6 +71,10 @@ final class ControllerReflector
 
     private function getClassAndMethod(string $controller)
     {
+        if (isset($this->controllers[$controller])) {
+            return $this->controllers[$controller];
+        }
+
         if (false === strpos($controller, '::') && 2 === substr_count($controller, ':')) {
             $controller = $this->controllerNameParser->parse($controller);
         }
@@ -98,9 +104,11 @@ final class ControllerReflector
         }
 
         if (!isset($class) || !isset($method)) {
+            $this->controllers[$controller] = null;
+
             return;
         }
 
-        return [$class, $method];
+        return $this->controllers[$controller] = [$class, $method];
     }
 }
diff --git a/composer.json b/composer.json
index 431a599..7fc9452 100644
--- a/composer.json
+++ b/composer.json
@@ -18,7 +18,8 @@
         "php": "~7.0|~7.1",
         "symfony/framework-bundle": "^2.8|^3.0",
         "symfony/property-info": "^2.8|^3.0",
-        "exsyst/swagger": "~0.2.3"
+        "exsyst/swagger": "~0.2.3",
+        "zircote/swagger-php": "dev-master"
     },
     "require-dev": {
         "symfony/twig-bundle": "^2.8|^3.0",
@@ -34,13 +35,11 @@
         "doctrine/annotations": "^1.2",
 
         "phpdocumentor/reflection-docblock": "^3.1",
-        "zircote/swagger-php": "^2.0",
         "api-platform/core": "^2.0",
         "friendsofsymfony/rest-bundle": "^2.0"
     },
     "suggest": {
         "phpdocumentor/reflection-docblock": "For parsing php docs.",
-        "zircote/swagger-php": "For using swagger annotations.",
         "api-platform/core": "For using an API oriented framework.",
         "friendsofsymfony/rest-bundle": "For using the parameters annotations."
     },