diff --git a/src/Symfony/Component/Form/Extension/Validator/ValidatorExtension.php b/src/Symfony/Component/Form/Extension/Validator/ValidatorExtension.php
index 88890ae651..5717ffb154 100644
--- a/src/Symfony/Component/Form/Extension/Validator/ValidatorExtension.php
+++ b/src/Symfony/Component/Form/Extension/Validator/ValidatorExtension.php
@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\Form\Extension\Validator;
 
+use Symfony\Component\Form\Exception\UnexpectedTypeException;
 use Symfony\Component\Form\Extension\Validator\Constraints\Form;
 use Symfony\Component\Form\AbstractExtension;
 use Symfony\Component\Validator\Constraints\Valid;
@@ -29,23 +30,19 @@ class ValidatorExtension extends AbstractExtension
 
     /**
      * @param ValidatorInterface|LegacyValidatorInterface $validator
+     *
+     * @throws UnexpectedTypeException If $validator is invalid
      */
     public function __construct($validator)
     {
-        // since validator apiVersion 2.5
+        // 2.5 API
         if ($validator instanceof ValidatorInterface) {
-            $this->validator = $validator;
-
-            /** @var $metadata ClassMetadata */
-            $metadata = $this->validator->getMetadataFor('Symfony\Component\Form\Form');
-        // until validator apiVersion 2.4
+            $metadata = $validator->getMetadataFor('Symfony\Component\Form\Form');
+        // 2.4 API
         } elseif ($validator instanceof LegacyValidatorInterface) {
-            $this->validator = $validator;
-
-            /** @var $metadata ClassMetadata */
-            $metadata = $this->validator->getMetadataFactory()->getMetadataFor('Symfony\Component\Form\Form');
+            $metadata = $validator->getMetadataFactory()->getMetadataFor('Symfony\Component\Form\Form');
         } else {
-            throw new \InvalidArgumentException('Validator must be instance of Symfony\Component\Validator\Validator\ValidatorInterface or Symfony\Component\Validator\ValidatorInterface');
+            throw new UnexpectedTypeException($validator, 'Symfony\Component\Validator\Validator\ValidatorInterface or Symfony\Component\Validator\ValidatorInterface');
         }
 
         // Register the form constraints in the validator programmatically.
@@ -53,13 +50,22 @@ class ValidatorExtension extends AbstractExtension
         // the DIC, where the XML file is loaded automatically. Thus the following
         // code must be kept synchronized with validation.xml
 
+        /** @var $metadata ClassMetadata */
         $metadata->addConstraint(new Form());
         $metadata->addPropertyConstraint('children', new Valid());
+
+        $this->validator = $validator;
     }
 
     public function loadTypeGuesser()
     {
-        return new ValidatorTypeGuesser($this->validator->getMetadataFactory());
+        // 2.4 API
+        if ($this->validator instanceof LegacyValidatorInterface) {
+            return new ValidatorTypeGuesser($this->validator->getMetadataFactory());
+        }
+
+        // 2.5 API - ValidatorInterface extends MetadataFactoryInterface
+        return new ValidatorTypeGuesser($this->validator);
     }
 
     protected function loadTypeExtensions()
diff --git a/src/Symfony/Component/Form/Tests/Extension/Validator/ValidatorExtensionTest.php b/src/Symfony/Component/Form/Tests/Extension/Validator/ValidatorExtensionTest.php
index bc69231fe2..eca0873818 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Validator/ValidatorExtensionTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Validator/ValidatorExtensionTest.php
@@ -15,79 +15,70 @@ use Symfony\Component\Form\Extension\Validator\ValidatorExtension;
 
 class ValidatorExtensionTest extends \PHPUnit_Framework_TestCase
 {
-    public function testValidatorInterfaceSinceSymfony25()
+    public function test2Dot5ValidationApi()
     {
-        $classMetaData = $this->createClassMetaDataMock();
-
-        // Mock of ValidatorInterface since apiVersion 2.5
         $validator = $this->getMock('Symfony\Component\Validator\Validator\ValidatorInterface');
+        $metadata = $this->getMockBuilder('Symfony\Component\Validator\Mapping\ClassMetadata')
+            ->disableOriginalConstructor()
+            ->getMock();
 
-        $validator
-            ->expects($this->once())
+        $validator->expects($this->once())
             ->method('getMetadataFor')
             ->with($this->identicalTo('Symfony\Component\Form\Form'))
-            ->will($this->returnValue($classMetaData))
-        ;
+            ->will($this->returnValue($metadata));
 
-        $validatorExtension = new ValidatorExtension($validator);
-        $this->assertAttributeSame($validator, 'validator', $validatorExtension);
+        // Verify that the constraints are added
+        $metadata->expects($this->once())
+            ->method('addConstraint')
+            ->with($this->isInstanceOf('Symfony\Component\Form\Extension\Validator\Constraints\Form'));
+
+        $metadata->expects($this->once())
+            ->method('addPropertyConstraint')
+            ->with('children', $this->isInstanceOf('Symfony\Component\Validator\Constraints\Valid'));
+
+        $extension = new ValidatorExtension($validator);
+        $guesser = $extension->loadTypeGuesser();
+
+        $this->assertInstanceOf('Symfony\Component\Form\Extension\Validator\ValidatorTypeGuesser', $guesser);
     }
 
-    public function testValidatorInterfaceUntilSymfony24()
+    public function test2Dot4ValidationApi()
     {
-        $classMetaData = $this->createClassMetaDataMock();
+        $factory = $this->getMock('Symfony\Component\Validator\MetadataFactoryInterface');
+        $validator = $this->getMock('Symfony\Component\Validator\ValidatorInterface');
+        $metadata = $this->getMockBuilder('Symfony\Component\Validator\Mapping\ClassMetadata')
+            ->disableOriginalConstructor()
+            ->getMock();
 
-        $metaDataFactory = $this->getMock('Symfony\Component\Validator\MetadataFactoryInterface');
+        $validator->expects($this->any())
+            ->method('getMetadataFactory')
+            ->will($this->returnValue($factory));
 
-        $metaDataFactory
-            ->expects($this->once())
+        $factory->expects($this->once())
             ->method('getMetadataFor')
             ->with($this->identicalTo('Symfony\Component\Form\Form'))
-            ->will($this->returnValue($classMetaData))
-        ;
+            ->will($this->returnValue($metadata));
 
-        // Mock of ValidatorInterface until apiVersion 2.4
-        $validator = $this->getMock('Symfony\Component\Validator\ValidatorInterface');
+        // Verify that the constraints are added
+        $metadata->expects($this->once())
+            ->method('addConstraint')
+            ->with($this->isInstanceOf('Symfony\Component\Form\Extension\Validator\Constraints\Form'));
 
-        $validator
-            ->expects($this->once())
-            ->method('getMetadataFactory')
-            ->will($this->returnValue($metaDataFactory))
-        ;
+        $metadata->expects($this->once())
+            ->method('addPropertyConstraint')
+            ->with('children', $this->isInstanceOf('Symfony\Component\Validator\Constraints\Valid'));
 
-        $validatorExtension = new ValidatorExtension($validator);
-        $this->assertAttributeSame($validator, 'validator', $validatorExtension);
+        $extension = new ValidatorExtension($validator);
+        $guesser = $extension->loadTypeGuesser();
+
+        $this->assertInstanceOf('Symfony\Component\Form\Extension\Validator\ValidatorTypeGuesser', $guesser);
     }
 
     /**
-     * @expectedException \InvalidArgumentException
+     * @expectedException \Symfony\Component\Form\Exception\UnexpectedTypeException
      */
     public function testInvalidValidatorInterface()
     {
         new ValidatorExtension(null);
     }
-
-    /**
-     * @return mixed
-     */
-    private function createClassMetaDataMock()
-    {
-        $classMetaData = $this->getMockBuilder('Symfony\Component\Validator\Mapping\ClassMetadata')
-            ->disableOriginalConstructor()
-            ->getMock();
-
-        $classMetaData
-            ->expects($this->once())
-            ->method('addConstraint')
-            ->with($this->isInstanceOf('Symfony\Component\Form\Extension\Validator\Constraints\Form'));
-        $classMetaData
-            ->expects($this->once())
-            ->method('addPropertyConstraint')
-            ->with(
-                $this->identicalTo('children'),
-                $this->isInstanceOf('Symfony\Component\Validator\Constraints\Valid')
-            );
-
-        return $classMetaData;
-    }
 }