diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Validator/ConstraintValidatorFactoryTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Validator/ConstraintValidatorFactoryTest.php
index 7dc3389939..efdff8197b 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Validator/ConstraintValidatorFactoryTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Validator/ConstraintValidatorFactoryTest.php
@@ -43,7 +43,7 @@ class ConstraintValidatorFactoryTest extends \PHPUnit_Framework_TestCase
     {
         $service = 'validator_constraint_service';
         $alias = 'validator_constraint_alias';
-        $validator = new \stdClass();
+        $validator = $this->getMockForAbstractClass('Symfony\\Component\\Validator\\ConstraintValidator');
 
         // mock ContainerBuilder b/c it implements TaggedContainerInterface
         $container = $this->getMock('Symfony\\Component\\DependencyInjection\\ContainerBuilder');
diff --git a/src/Symfony/Bundle/FrameworkBundle/Validator/ConstraintValidatorFactory.php b/src/Symfony/Bundle/FrameworkBundle/Validator/ConstraintValidatorFactory.php
index 86e2f99454..66f0d012d3 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Validator/ConstraintValidatorFactory.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Validator/ConstraintValidatorFactory.php
@@ -14,7 +14,8 @@ namespace Symfony\Bundle\FrameworkBundle\Validator;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidatorFactoryInterface;
-use Symfony\Component\Validator\ConstraintValidator;
+use Symfony\Component\Validator\ConstraintValidatorInterface;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
 
 /**
  * Uses a service container to create constraint validators.
@@ -58,7 +59,9 @@ class ConstraintValidatorFactory implements ConstraintValidatorFactoryInterface
      *
      * @param Constraint $constraint A constraint
      *
-     * @return ConstraintValidator A validator for the supplied constraint
+     * @return ConstraintValidatorInterface A validator for the supplied constraint
+     *
+     * @throws UnexpectedTypeException When the validator is not an instance of ConstraintValidatorInterface
      */
     public function getInstance(Constraint $constraint)
     {
@@ -70,6 +73,10 @@ class ConstraintValidatorFactory implements ConstraintValidatorFactoryInterface
             $this->validators[$name] = $this->container->get($this->validators[$name]);
         }
 
+        if (!$this->validators[$name] instanceof ConstraintValidatorInterface) {
+            throw new UnexpectedTypeException($this->validators[$name], 'Symfony\Component\Validator\ConstraintValidatorInterface');
+        }
+
         return $this->validators[$name];
     }
 }