diff --git a/lib/Doctrine/ORM/UnitOfWork.php b/lib/Doctrine/ORM/UnitOfWork.php
index 5088bb273..76ce5219a 100644
--- a/lib/Doctrine/ORM/UnitOfWork.php
+++ b/lib/Doctrine/ORM/UnitOfWork.php
@@ -1509,7 +1509,9 @@ class UnitOfWork implements PropertyChangedListener
         
         switch ($this->getEntityState($entity, self::STATE_DETACHED)) {
             case self::STATE_MANAGED:
-                $this->removeFromIdentityMap($entity);
+                if ($this->isInIdentityMap($entity)) {
+                    $this->removeFromIdentityMap($entity);
+                }
                 unset($this->entityInsertions[$oid], $this->entityUpdates[$oid],
                         $this->entityDeletions[$oid], $this->entityIdentifiers[$oid],
                         $this->entityStates[$oid], $this->originalEntityData[$oid]);
diff --git a/tests/Doctrine/Tests/ORM/Functional/DetachedEntityTest.php b/tests/Doctrine/Tests/ORM/Functional/DetachedEntityTest.php
index a993606cf..30069a37b 100644
--- a/tests/Doctrine/Tests/ORM/Functional/DetachedEntityTest.php
+++ b/tests/Doctrine/Tests/ORM/Functional/DetachedEntityTest.php
@@ -173,5 +173,23 @@ class DetachedEntityTest extends \Doctrine\Tests\OrmFunctionalTestCase
         $this->assertType('Doctrine\Tests\Models\CMS\CmsUser', $newUser);
         $this->assertEquals('gblanco', $newUser->username);
     }
+
+    /**
+     * @group DDC-920
+     */
+    public function testDetachManagedUnpersistedEntity()
+    {
+        $user = new CmsUser;
+        $user->name = 'Guilherme';
+        $user->username = 'gblanco';
+        $user->status = 'developer';
+
+        $this->_em->persist($user);
+        $this->_em->detach($user);
+
+        $this->_em->flush();
+
+        $this->assertNull($user->id);
+    }
 }