diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 34b3c530b3..80ec236edb 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -793,11 +793,13 @@ class Query(object):
                     lhs_col = int_opts.parents[int_model].column
                     int_opts = int_model._meta
                     alias = self.join((alias, int_opts.db_table, lhs_col,
-                            int_opts.pk.column), exclusions=used)
+                            int_opts.pk.column), exclusions=used,
+                            promote=f.null)
             else:
                 alias = root_alias
             alias = self.join((alias, table, f.column,
-                    f.rel.get_related_field().column), exclusions=used)
+                    f.rel.get_related_field().column), exclusions=used,
+                    promote=f.null)
             used.add(alias)
             self.select.extend([(alias, f2.column)
                     for f2 in f.rel.to._meta.fields])
diff --git a/tests/regressiontests/queries/models.py b/tests/regressiontests/queries/models.py
index 39f13d616d..f80d1eb827 100644
--- a/tests/regressiontests/queries/models.py
+++ b/tests/regressiontests/queries/models.py
@@ -561,6 +561,10 @@ Multiple filter statements are joined using "AND" all the time.
 >>> Author.objects.filter(Q(extra__note=n1)|Q(item__note=n3)).filter(id=a1.id)
 [<Author: a1>]
 
+Bug #6981
+>>> Tag.objects.select_related('parent').order_by('name')
+[<Tag: t1>, <Tag: t2>, <Tag: t3>, <Tag: t4>, <Tag: t5>]
+
 Bug #6180, #6203
 >>> Item.objects.count()
 4