Use a more explicit check for whether these ids are None.

1 files changed, 2 insertions, 2 deletions

diff --git a/django/contrib/contenttypes/generic.py b/django/contrib/contenttypes/generic.py
index 04d4894b8a..6f120f82e0 100644
--- a/django/contrib/contenttypes/generic.py
+++ b/django/contrib/contenttypes/generic.py
@@ -66,7 +66,7 @@ class GenericForeignKey(six.with_metaclass(RenameGenericForeignKeyMethods)):
         if obj is not None:
             return ContentType.objects.db_manager(obj._state.db).get_for_model(
                 obj, for_concrete_model=self.for_concrete_model)
-        elif id:
+        elif id is not None:
             return ContentType.objects.db_manager(using).get_for_id(id)
         else:
             # This should never happen. I love comments like this, don't you?
@@ -130,7 +130,7 @@ class GenericForeignKey(six.with_metaclass(RenameGenericForeignKeyMethods)):
             # performance when dealing with GFKs in loops and such.
             f = self.model._meta.get_field(self.ct_field)
             ct_id = getattr(instance, f.get_attname(), None)
-            if ct_id:
+            if ct_id is not None:
                 ct = self.get_content_type(id=ct_id, using=instance._state.db)
                 try:
                     rel_obj = ct.get_object_for_this_type(pk=getattr(instance, self.fk_field))