diff --git a/lib/Doctrine/ORM/AbstractQuery.php b/lib/Doctrine/ORM/AbstractQuery.php
index 0f0078a7e..6dda4d2f8 100644
--- a/lib/Doctrine/ORM/AbstractQuery.php
+++ b/lib/Doctrine/ORM/AbstractQuery.php
@@ -296,6 +296,7 @@ abstract class AbstractQuery
      */
     public function setResultSetMapping(Query\ResultSetMapping $rsm)
     {
+        $rsm->translateNamespaces($this->_em);
         $this->_resultSetMapping = $rsm;
 
         return $this;
diff --git a/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php b/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php
index bc28aa072..04d741cbb 100644
--- a/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php
+++ b/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php
@@ -83,7 +83,7 @@ class ObjectHydrator extends AbstractHydrator
      */
     private $existingCollections = array();
 
-     /**
+    /**
      * {@inheritdoc}
      */
     protected function prepare()
@@ -525,7 +525,7 @@ class ObjectHydrator extends AbstractHydrator
                 // check for existing result from the iterations before
                 if ( ! isset($this->identifierMap[$dqlAlias][$id[$dqlAlias]])) {
                     $element = $this->getEntity($rowData[$dqlAlias], $dqlAlias);
-   
+
                     if ($this->_rsm->isMixed) {
                         $element = array($entityKey => $element);
                     }
@@ -597,7 +597,7 @@ class ObjectHydrator extends AbstractHydrator
 
                 if ($count === 1) {
                     $result[$resultKey] = $obj;
-                    
+
                     continue;
                 }
 
diff --git a/lib/Doctrine/ORM/Query/ResultSetMapping.php b/lib/Doctrine/ORM/Query/ResultSetMapping.php
index 9dbe9bc63..1461f4f4c 100644
--- a/lib/Doctrine/ORM/Query/ResultSetMapping.php
+++ b/lib/Doctrine/ORM/Query/ResultSetMapping.php
@@ -19,6 +19,8 @@
 
 namespace Doctrine\ORM\Query;
 
+use Doctrine\ORM\EntityManager;
+
 /**
  * A ResultSetMapping describes how a result set of an SQL query maps to a Doctrine result.
  *
@@ -543,4 +545,27 @@ class ResultSetMapping
 
         return $this;
     }
+
+    /**
+     * Allows to translate entity namespaces to full qualified names.
+     *
+     * @param EntityManager $em
+     *
+     * @return void
+     */
+    public function translateNamespaces(EntityManager $em)
+    {
+        $fqcn = array();
+
+        $translate = function (&$alias) use ($em, &$fqcn) {
+            if ( ! isset($fqcn[$alias])) {
+                $fqcn[$alias] = $em->getClassMetadata($alias)->getName();
+            }
+            $alias = $fqcn[$alias];
+        };
+
+        array_walk($this->aliasMap, $translate);
+        array_walk($this->declaringClasses, $translate);
+    }
 }
+
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2256Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2256Test.php
new file mode 100644
index 000000000..949091f77
--- /dev/null
+++ b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2256Test.php
@@ -0,0 +1,115 @@
+<?php
+
+namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use Doctrine\ORM\Query\ResultSetMapping;
+use Doctrine\ORM\Query\ResultSetMappingBuilder;
+
+/**
+ * @group DDC-2256
+ */
+class DDC2256Test extends \Doctrine\Tests\OrmFunctionalTestCase
+{
+    protected function setup()
+    {
+        parent::setup();
+        $this->_schemaTool->createSchema(array(
+            $this->_em->getClassMetadata(__NAMESPACE__ . '\DDC2256User'),
+            $this->_em->getClassMetadata(__NAMESPACE__ . '\DDC2256Group')
+        ));
+    }
+
+    public function testIssue()
+    {
+        $config = $this->_em->getConfiguration();
+        $config->addEntityNamespace('MyNamespace', 'Doctrine\Tests\ORM\Functional\Ticket');
+
+        $user = new DDC2256User();
+        $user->name = 'user';
+        $group = new DDC2256Group();
+        $group->name = 'group';
+        $user->group = $group;
+
+        $this->_em->persist($user);
+        $this->_em->persist($group);
+        $this->_em->flush();
+        $this->_em->clear();
+
+        $sql = 'SELECT u.id, u.name, g.id as group_id, g.name as group_name FROM ddc2256_users u LEFT JOIN ddc2256_groups g ON u.group_id = g.id';
+
+        // Test ResultSetMapping.
+        $rsm = new ResultSetMapping();
+
+        $rsm->addEntityResult('MyNamespace:DDC2256User', 'u');
+        $rsm->addFieldResult('u', 'id', 'id');
+        $rsm->addFieldResult('u', 'name', 'name');
+
+        $rsm->addJoinedEntityResult('MyNamespace:DDC2256Group', 'g', 'u', 'group');
+        $rsm->addFieldResult('g', 'group_id', 'id');
+        $rsm->addFieldResult('g', 'group_name', 'name');
+
+        $this->_em->createNativeQuery($sql, $rsm)->getResult();
+
+        // Test ResultSetMappingBuilder.
+        $rsm = new ResultSetMappingBuilder($this->_em);
+        $rsm->addRootEntityFromClassMetadata('MyNamespace:DDC2256User', 'u');
+        $rsm->addJoinedEntityFromClassMetadata('MyNamespace:DDC2256Group', 'g', 'u', 'group', array('id' => 'group_id', 'name' => 'group_name'));
+
+        $this->_em->createNativeQuery($sql, $rsm)->getResult();
+    }
+}
+
+/**
+ * @Entity
+ * @Table(name="ddc2256_users")
+ */
+class DDC2256User
+{
+    /**
+     * @Id
+     * @Column(type="integer")
+     * @GeneratedValue(strategy="AUTO")
+     */
+    public $id;
+
+    /**
+     * @Column(type="string")
+     */
+    public $name;
+
+    /**
+     * @ManyToOne(targetEntity="DDC2256Group", inversedBy="users")A
+     * @JoinColumn(name="group_id")
+     */
+    public $group;
+}
+
+/**
+ * @Entity
+ * @Table(name="ddc2256_groups")
+ */
+class DDC2256Group
+{
+    /**
+     * @Id
+     * @Column(type="integer")
+     * @GeneratedValue(strategy="AUTO")
+     */
+    public $id;
+
+    /**
+     * @Column(type="string")
+     */
+    public $name;
+
+    /**
+     * @OneToMany(targetEntity="DDC2256User", mappedBy="group")
+     */
+    public $users;
+
+    public function __construct()
+    {
+        $this->users = new \Doctrine\Common\Collections\ArrayCollection();
+    }
+}
+