diff -r 40e2940605a3 -r 4bec0525ef1b src/linetypes/quadrilateral.h
--- a/src/linetypes/quadrilateral.h	Wed Mar 18 17:11:23 2020 +0200
+++ b/src/linetypes/quadrilateral.h	Thu Mar 19 21:06:06 2020 +0200
@@ -18,11 +18,12 @@
 		Color colorIndex = ldraw::mainColor);
 	Quadrilateral(const std::array<glm::vec3, 4>& vertices, const Color color);
 	QVariant getProperty(Property id) const override;
-	SetPropertyResult setProperty(Property id, const QVariant& value) override;
 	QString textRepresentation() const override;
 	void getPolygons(std::vector<gl::Polygon>& polygons, GetPolygonsContext* context) const override;
 	void invert() override;
 	int numPoints() const override;
 	const glm::vec3& getPoint(int index) const override;
 	glm::vec3 points[4] = {{}};
+protected:
+	void setProperty(SetPropertyResult* result, const PropertyKeyValue& pair) override;
 };