diff -r e2080ac44039 -r 488d0ba6070b src/linetypes/quadrilateral.cpp
--- a/src/linetypes/quadrilateral.cpp	Fri Sep 17 22:43:22 2021 +0300
+++ b/src/linetypes/quadrilateral.cpp	Tue Sep 21 16:00:15 2021 +0300
@@ -29,3 +29,8 @@
 	// -> 2 1 0 3
 	std::swap(this->points[0], this->points[2]);
 }
+
+ldraw::Object::Type ldraw::Quadrilateral::typeIdentifier() const
+{
+	return Type::Quadrilateral;
+}