diff --git a/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php b/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php
index 14aed2a67..d2d23a252 100644
--- a/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php
+++ b/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php
@@ -251,12 +251,13 @@ class ObjectHydrator extends AbstractHydrator
             }
 
             $discrMap = $this->_metadataCache[$className]->discriminatorMap;
+            $discriminatorValue = (string) $data[$discrColumn];
 
-            if ( ! isset($discrMap[$data[$discrColumn]])) {
-                throw HydrationException::invalidDiscriminatorValue($data[$discrColumn], array_keys($discrMap));
+            if ( ! isset($discrMap[$discriminatorValue])) {
+                throw HydrationException::invalidDiscriminatorValue($discriminatorValue, array_keys($discrMap));
             }
 
-            $className = $discrMap[$data[$discrColumn]];
+            $className = $discrMap[$discriminatorValue];
 
             unset($data[$discrColumn]);
         }
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/GH6141Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/GH6141Test.php
new file mode 100644
index 000000000..3ca71928d
--- /dev/null
+++ b/tests/Doctrine/Tests/ORM/Functional/Ticket/GH6141Test.php
@@ -0,0 +1,195 @@
+<?php
+namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use Doctrine\DBAL\Platforms\AbstractPlatform;
+use Doctrine\DBAL\Types\StringType;
+use Doctrine\DBAL\Types\Type;
+use Doctrine\ORM\AbstractQuery;
+use Doctrine\Tests\OrmFunctionalTestCase;
+
+class GH6141Test extends OrmFunctionalTestCase
+{
+    protected function setUp()
+    {
+        parent::setUp();
+
+        Type::addType(GH6141PeopleType::NAME, GH6141PeopleType::class);
+
+        $this->_schemaTool->createSchema(
+            [
+                $this->_em->getClassMetadata(GH6141Person::class),
+                $this->_em->getClassMetadata(GH6141Boss::class),
+                $this->_em->getClassMetadata(GH6141Employee::class),
+            ]
+        );
+    }
+
+    public function testEnumDiscriminatorsShouldBeConvertedToString()
+    {
+        $boss = new GH6141Boss('John');
+        $employee = new GH6141Employee('Bob');
+
+        $this->_em->persist($boss);
+        $this->_em->persist($employee);
+        $this->_em->flush();
+        $this->_em->clear();
+
+        // Using DQL here to make sure that we'll use ObjectHydrator instead of SimpleObjectHydrator
+        $query = $this->_em->createQueryBuilder()
+            ->select('person')
+            ->from(GH6141Person::class, 'person')
+            ->where('person.name = :name')
+            ->setMaxResults(1)
+            ->getQuery();
+
+        $query->setParameter('name', 'John');
+        self::assertEquals($boss, $query->getOneOrNullResult(AbstractQuery::HYDRATE_OBJECT));
+        self::assertEquals(
+            GH6141People::get(GH6141People::BOSS),
+            $query->getOneOrNullResult(AbstractQuery::HYDRATE_ARRAY)['discr']
+        );
+
+        $query->setParameter('name', 'Bob');
+        self::assertEquals($employee, $query->getOneOrNullResult(AbstractQuery::HYDRATE_OBJECT));
+        self::assertEquals(
+            GH6141People::get(GH6141People::EMPLOYEE),
+            $query->getOneOrNullResult(AbstractQuery::HYDRATE_ARRAY)['discr']
+        );
+    }
+}
+
+class GH6141PeopleType extends StringType
+{
+    const NAME = 'gh6141people';
+
+    /**
+     * {@inheritdoc}
+     */
+    public function convertToDatabaseValue($value, AbstractPlatform $platform)
+    {
+        if (!$value instanceof GH6141People) {
+            $value = GH6141People::get($value);
+        }
+
+        return (string) $value;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function convertToPhpValue($value, AbstractPlatform $platform)
+    {
+        return GH6141People::get($value);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getName()
+    {
+        return self::NAME;
+    }
+}
+
+class GH6141People
+{
+    const BOSS = 'boss';
+    const EMPLOYEE = 'employee';
+
+    /**
+     * @var string
+     */
+    private $value;
+
+    /**
+     * @param string $value
+     *
+     * @return GH6141People
+     *
+     * @throws \InvalidArgumentException
+     */
+    public static function get($value)
+    {
+        if (!self::isValid($value)) {
+            throw new \InvalidArgumentException();
+        }
+
+        return new self($value);
+    }
+
+    /**
+     * @param string $valid
+     *
+     * @return bool
+     */
+    private static function isValid($valid)
+    {
+        return in_array($valid, [self::BOSS, self::EMPLOYEE]);
+    }
+
+    /**
+     * @param string $value
+     */
+    private function __construct($value)
+    {
+        $this->value = $value;
+    }
+
+    /**
+     * @return string
+     */
+    public function getValue()
+    {
+        return $this->value;
+    }
+
+    /**
+     * @return string
+     */
+    public function __toString()
+    {
+        return $this->value;
+    }
+}
+
+/**
+ * @Entity
+ * @InheritanceType("JOINED")
+ * @DiscriminatorColumn(name="discr", type="gh6141people")
+ * @DiscriminatorMap({
+ *      "boss"     = GH6141Boss::class,
+ *      "employee" = GH6141Employee::class
+ * })
+ */
+abstract class GH6141Person
+{
+    /**
+     * @Id
+     * @Column(type="integer")
+     * @GeneratedValue(strategy="AUTO")
+     */
+    public $id;
+
+    /**
+     * @Column(type="string")
+     */
+    public $name;
+
+    /**
+     * @param string $name
+     */
+    public function __construct($name)
+    {
+        $this->name = $name;
+    }
+}
+
+/** @Entity */
+class GH6141Boss extends GH6141Person
+{
+}
+
+/** @Entity */
+class GH6141Employee extends GH6141Person
+{
+}