diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
index 15e0801fb9..cd4f967b4e 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
@@ -718,6 +718,7 @@ class FrameworkExtension extends Extension
             switch ($config['api']) {
                 case '2.4':
                     $api = Validation::API_VERSION_2_4;
+                    $container->setParameter('validator.validator_factory.class', $container->getParameter('validator.legacy_validator_factory.class'));
                     break;
                 case '2.5':
                     $api = Validation::API_VERSION_2_5;
diff --git a/src/Symfony/Bundle/FrameworkBundle/Resources/config/validator.xml b/src/Symfony/Bundle/FrameworkBundle/Resources/config/validator.xml
index 336379a11b..e0cd37d6b1 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Resources/config/validator.xml
+++ b/src/Symfony/Bundle/FrameworkBundle/Resources/config/validator.xml
@@ -11,6 +11,7 @@
         <parameter key="validator.mapping.cache.apc.class">Symfony\Component\Validator\Mapping\Cache\ApcCache</parameter>
         <parameter key="validator.mapping.cache.prefix" />
         <parameter key="validator.validator_factory.class">Symfony\Bundle\FrameworkBundle\Validator\ConstraintValidatorFactory</parameter>
+        <parameter key="validator.legacy_validator_factory.class">Symfony\Bundle\FrameworkBundle\Validator\LegacyConstraintValidatorFactory</parameter>
         <parameter key="validator.expression.class">Symfony\Component\Validator\Constraints\ExpressionValidator</parameter>
         <parameter key="validator.email.class">Symfony\Component\Validator\Constraints\EmailValidator</parameter>
     </parameters>
diff --git a/src/Symfony/Bundle/FrameworkBundle/Validator/LegacyConstraintValidatorFactory.php b/src/Symfony/Bundle/FrameworkBundle/Validator/LegacyConstraintValidatorFactory.php
new file mode 100644
index 0000000000..ac85eb4fb5
--- /dev/null
+++ b/src/Symfony/Bundle/FrameworkBundle/Validator/LegacyConstraintValidatorFactory.php
@@ -0,0 +1,91 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bundle\FrameworkBundle\Validator;
+
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidatorFactoryInterface;
+use Symfony\Component\Validator\ConstraintValidatorInterface;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+
+/**
+ * Like {@link ConstraintValidatorFactory}, but aware of services compatible
+ * with the 2.4 API.
+ *
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ * @author Kris Wallsmith <kris@symfony.com>
+ *
+ * @see ConstraintValidatorFactory
+ */
+class LegacyConstraintValidatorFactory implements ConstraintValidatorFactoryInterface
+{
+    const BASE_NAMESPACE = 'Symfony\\Component\\Validator\\Constraints';
+
+    protected $container;
+    protected $validators;
+
+    /**
+     * Constructor.
+     *
+     * @param ContainerInterface $container  The service container
+     * @param array              $validators An array of validators
+     */
+    public function __construct(ContainerInterface $container, array $validators = array())
+    {
+        $this->container = $container;
+        $this->validators = $validators;
+    }
+
+    /**
+     * Returns the validator for the supplied constraint.
+     *
+     * @param Constraint $constraint A 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)
+    {
+        $name = $constraint->validatedBy();
+
+        if (!isset($this->validators[$name])) {
+            switch (get_class($constraint)) {
+                case self::BASE_NAMESPACE.'\\All':
+                    $name = self::BASE_NAMESPACE.'\\LegacyAllValidator';
+                    break;
+                case self::BASE_NAMESPACE.'\\Choice':
+                    $name = self::BASE_NAMESPACE.'\\LegacyChoiceValidator';
+                    break;
+                case self::BASE_NAMESPACE.'\\Collection':
+                    $name = self::BASE_NAMESPACE.'\\LegacyCollectionValidator';
+                    break;
+                case self::BASE_NAMESPACE.'\\Count':
+                    $name = self::BASE_NAMESPACE.'\\LegacyCountValidator';
+                    break;
+                case self::BASE_NAMESPACE.'\\Length':
+                    $name = self::BASE_NAMESPACE.'\\LegacyLengthValidator';
+                    break;
+            }
+
+            $this->validators[$name] = new $name();
+        } elseif (is_string($this->validators[$name])) {
+            $this->validators[$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];
+    }
+}