diff --git a/mongoengine/fields.py b/mongoengine/fields.py
index 01d3fc63..ee029065 100644
--- a/mongoengine/fields.py
+++ b/mongoengine/fields.py
@@ -777,7 +777,7 @@ class ReferenceField(BaseField):
     def to_mongo(self, document):
         if isinstance(document, DBRef):
             if not self.dbref:
-                return DBRef.id
+                return document.id
             return document
         elif not self.dbref and isinstance(document, basestring):
             return document
diff --git a/tests/test_fields.py b/tests/test_fields.py
index 98065501..abc50a3f 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -1104,6 +1104,15 @@ class FieldTest(unittest.TestCase):
 
         p = Person.objects.get(name="Ross")
         self.assertEqual(p.parent, p1)
+        
+    def test_dbref_to_mongo(self):
+        class Person(Document):
+            name = StringField()
+            parent = ReferenceField('self', dbref=False)
+    
+        p1 = Person._from_son({'name':"Yakxxx", 'parent': "50a234ea469ac1eda42d347d"})
+        mongoed = p1.to_mongo()
+        self.assertIsInstance(mongoed['parent'], ObjectId)
 
     def test_objectid_reference_fields(self):