diff --git a/src/ifcparse/aggregate_of_instance.h b/src/ifcparse/aggregate_of_instance.h
index 59f335f79d..c6bf8f5921 100644
--- a/src/ifcparse/aggregate_of_instance.h
+++ b/src/ifcparse/aggregate_of_instance.h
@@ -45,8 +45,11 @@ public:
 	template <class U>
 	typename U::list::ptr as() {
 		typename U::list::ptr r(new typename U::list);
-		const bool all = !U::Class().as_entity();
-		for (it i = begin(); i != end(); ++i) if (all || (*i)->declaration().is(U::Class())) r->push((U*)*i);
+		for (it i = begin(); i != end(); ++i) {
+			if ((*i)->as<U>()) {
+				r->push((*i)->as<U>());
+			}
+		}
 		return r;
 	}
 	void remove(IfcUtil::IfcBaseClass*);