diff --git a/private/attributes b/private/attributes
index cf1c307..991bac1 100644
--- a/private/attributes
+++ b/private/attributes
@@ -9,3 +9,4 @@
 # and vendor_property_type. Such types are ill-formed because
 # property owner attributes must be exclusive.
 attribute system_and_vendor_property_type;
+expandattribute system_and_vendor_property_type false;