diff --git a/lib/Doctrine/ORM/Internal/Hydration/SimpleObjectHydrator.php b/lib/Doctrine/ORM/Internal/Hydration/SimpleObjectHydrator.php
index 1c21369e3..5fb77d67e 100644
--- a/lib/Doctrine/ORM/Internal/Hydration/SimpleObjectHydrator.php
+++ b/lib/Doctrine/ORM/Internal/Hydration/SimpleObjectHydrator.php
@@ -122,6 +122,9 @@ class SimpleObjectHydrator extends AbstractHydrator
                 continue;
             }
 
+            // Check if value is null before conversion (because some types convert null to something else)
+            $valueIsNull = null === $value;
+
             // Convert field to a valid PHP value
             if (isset($cacheKeyInfo['type'])) {
                 $type  = $cacheKeyInfo['type'];
@@ -131,7 +134,7 @@ class SimpleObjectHydrator extends AbstractHydrator
             $fieldName = $cacheKeyInfo['fieldName'];
 
             // Prevent overwrite in case of inherit classes using same property name (See AbstractHydrator)
-            if ( ! isset($data[$fieldName]) || $value !== null) {
+            if ( ! isset($data[$fieldName]) || ! $valueIsNull) {
                 $data[$fieldName] = $value;
             }
         }
diff --git a/tests/Doctrine/Tests/Models/Issue5989/Issue5989Employee.php b/tests/Doctrine/Tests/Models/Issue5989/Issue5989Employee.php
new file mode 100644
index 000000000..9f5e248d8
--- /dev/null
+++ b/tests/Doctrine/Tests/Models/Issue5989/Issue5989Employee.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace Doctrine\Tests\Models\Issue5989;
+
+/**
+ * @Entity
+ * @Table(name="issue5989_employees")
+ */
+class Issue5989Employee extends Issue5989Person
+{
+    /**
+     * @Column(type="simple_array", nullable=true)
+     *
+     * @var array
+     */
+    public $tags;
+}
diff --git a/tests/Doctrine/Tests/Models/Issue5989/Issue5989Manager.php b/tests/Doctrine/Tests/Models/Issue5989/Issue5989Manager.php
new file mode 100644
index 000000000..e00067d9c
--- /dev/null
+++ b/tests/Doctrine/Tests/Models/Issue5989/Issue5989Manager.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace Doctrine\Tests\Models\Issue5989;
+
+/**
+ * @Entity
+ * @Table(name="issue5989_managers")
+ */
+class Issue5989Manager extends Issue5989Person
+{
+    /**
+     * @Column(type="simple_array", nullable=true)
+     *
+     * @var array
+     */
+    public $tags;
+}
diff --git a/tests/Doctrine/Tests/Models/Issue5989/Issue5989Person.php b/tests/Doctrine/Tests/Models/Issue5989/Issue5989Person.php
new file mode 100644
index 000000000..d31e65def
--- /dev/null
+++ b/tests/Doctrine/Tests/Models/Issue5989/Issue5989Person.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Doctrine\Tests\Models\Issue5989;
+
+/**
+ * @Entity
+ * @Table(name="issue5989_persons")
+ * @InheritanceType("JOINED")
+ * @DiscriminatorColumn(name="discr", type="string")
+ * @DiscriminatorMap({
+ *      "person"    = "Issue5989Person",
+ *      "manager"   = "Issue5989Manager",
+ *      "employee"  = "Issue5989Employee"
+ * })
+ */
+class Issue5989Person
+{
+    /**
+     * @Id
+     * @Column(type="integer")
+     * @GeneratedValue
+     */
+    public $id;
+}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/Issue5989Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/Issue5989Test.php
new file mode 100644
index 000000000..cf601b99a
--- /dev/null
+++ b/tests/Doctrine/Tests/ORM/Functional/Ticket/Issue5989Test.php
@@ -0,0 +1,51 @@
+<?php
+
+namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use Doctrine\Tests\Models\Issue5989\Issue5989Employee;
+use Doctrine\Tests\Models\Issue5989\Issue5989Manager;
+use Doctrine\Tests\Models\Issue5989\Issue5989Person;
+
+/**
+ * @group issue-5989
+ */
+class Issue5989Test extends \Doctrine\Tests\OrmFunctionalTestCase
+{
+    public function setUp()
+    {
+        $this->useModelSet('issue5989');
+        parent::setUp();
+    }
+
+    public function testSimpleArrayTypeHydratedCorrectlyInJoinedInheritance()
+    {
+        $manager = new Issue5989Manager();
+
+        $managerTags = ['tag1', 'tag2'];
+        $manager->tags = $managerTags;
+        $this->_em->persist($manager);
+
+        $employee = new Issue5989Employee();
+
+        $employeeTags =['tag2', 'tag3'];
+        $employee->tags = $employeeTags;
+        $this->_em->persist($employee);
+
+        $this->_em->flush();
+
+        $managerId = $manager->id;
+        $employeeId = $employee->id;
+
+        // clear entity manager so that $repository->find actually fetches them and uses the hydrator
+        // instead of just returning the existing managed entities
+        $this->_em->clear();
+
+        $repository = $this->_em->getRepository(Issue5989Person::class);
+
+        $manager = $repository->find($managerId);
+        $employee = $repository->find($employeeId);
+
+        static::assertEquals($managerTags, $manager->tags);
+        static::assertEquals($employeeTags, $employee->tags);
+    }
+}
diff --git a/tests/Doctrine/Tests/ORM/Hydration/SimpleObjectHydratorTest.php b/tests/Doctrine/Tests/ORM/Hydration/SimpleObjectHydratorTest.php
index 459ce9ba1..9878728f2 100644
--- a/tests/Doctrine/Tests/ORM/Hydration/SimpleObjectHydratorTest.php
+++ b/tests/Doctrine/Tests/ORM/Hydration/SimpleObjectHydratorTest.php
@@ -86,4 +86,34 @@ class SimpleObjectHydratorTest extends HydrationTestCase
         $hydrator   = new \Doctrine\ORM\Internal\Hydration\SimpleObjectHydrator($this->_em);
         $hydrator->hydrateAll($stmt, $rsm);
     }
+
+    /**
+     * @group issue-5989
+     */
+    public function testNullValueShouldNotOverwriteFieldWithSameNameInJoinedInheritance()
+    {
+        $rsm = new ResultSetMapping;
+        $rsm->addEntityResult('Doctrine\Tests\Models\Issue5989\Issue5989Person', 'p');
+        $rsm->addFieldResult('p', 'p__id', 'id');
+        $rsm->addFieldResult('p', 'm__tags', 'tags', 'Doctrine\Tests\Models\Issue5989\Issue5989Manager');
+        $rsm->addFieldResult('p', 'e__tags', 'tags', 'Doctrine\Tests\Models\Issue5989\Issue5989Employee');
+        $rsm->addMetaResult('p', 'discr', 'discr', false, 'string');
+        $resultSet = array(
+            array(
+                'p__id'   => '1',
+                'm__tags' => 'tag1,tag2',
+                'e__tags' => null,
+                'discr'   => 'manager'
+            ),
+        );
+
+        $expectedEntity = new \Doctrine\Tests\Models\Issue5989\Issue5989Manager();
+        $expectedEntity->id = 1;
+        $expectedEntity->tags = ['tag1', 'tag2'];
+
+        $stmt       = new HydratorMockStatement($resultSet);
+        $hydrator   = new \Doctrine\ORM\Internal\Hydration\SimpleObjectHydrator($this->_em);
+        $result = $hydrator->hydrateAll($stmt, $rsm);
+        $this->assertEquals($result[0], $expectedEntity);
+    }
 }
diff --git a/tests/Doctrine/Tests/OrmFunctionalTestCase.php b/tests/Doctrine/Tests/OrmFunctionalTestCase.php
index b36a83487..611f357e8 100644
--- a/tests/Doctrine/Tests/OrmFunctionalTestCase.php
+++ b/tests/Doctrine/Tests/OrmFunctionalTestCase.php
@@ -284,6 +284,11 @@ abstract class OrmFunctionalTestCase extends OrmTestCase
             'Doctrine\Tests\Models\VersionedManyToOne\Category',
             'Doctrine\Tests\Models\VersionedManyToOne\Article',
         ),
+        'issue5989' => array(
+            'Doctrine\Tests\Models\Issue5989\Issue5989Person',
+            'Doctrine\Tests\Models\Issue5989\Issue5989Employee',
+            'Doctrine\Tests\Models\Issue5989\Issue5989Manager',
+        ),
     );
 
     /**
@@ -544,6 +549,12 @@ abstract class OrmFunctionalTestCase extends OrmTestCase
             $conn->executeUpdate('DELETE FROM versioned_many_to_one_category');
         }
 
+        if (isset($this->_usedModelSets['issue5989'])) {
+            $conn->executeUpdate('DELETE FROM issue5989_persons');
+            $conn->executeUpdate('DELETE FROM issue5989_employees');
+            $conn->executeUpdate('DELETE FROM issue5989_managers');
+        }
+
         $this->_em->clear();
     }