Index: docs/ref/models/fields.txt
===================================================================
--- docs/ref/models/fields.txt	(revision 9885)
+++ docs/ref/models/fields.txt	(working copy)
@@ -239,7 +239,7 @@
 field, a :exc:`django.db.IntegrityError` will be raised by the model's
 :meth:`~django.db.models.Model.save` method.
 
-This option is valid on all field types except :class:`ManyToManyField`.
+This option is valid on all field types except :class:`ManyToManyField` and :class:`FileField`.
 
 ``unique_for_date``
 -------------------