diff --git a/src/ifcgeom/ConversionResult.cpp b/src/ifcgeom/ConversionResult.cpp
index da29dc380e..30bed11214 100644
--- a/src/ifcgeom/ConversionResult.cpp
+++ b/src/ifcgeom/ConversionResult.cpp
@@ -8,3 +8,13 @@ IfcGeom::Representation::Triangulation * IfcGeom::ConversionResultShape::Triangu
 	Triangulate(settings, iden, t, -1);
 	return t;
 }
+
+using namespace ifcopenshell::geometry::taxonomy;
+
+void IfcGeom::ConversionResult::append(ifcopenshell::geometry::taxonomy::matrix4::ptr trsf) {
+	placement_ = make<matrix4>(placement_->ccomponents() * trsf->ccomponents());
+}
+
+void IfcGeom::ConversionResult::prepend(ifcopenshell::geometry::taxonomy::matrix4::ptr trsf) {
+	placement_ = make<matrix4>(trsf->ccomponents() * placement_->ccomponents());
+}
diff --git a/src/ifcgeom/ConversionResult.h b/src/ifcgeom/ConversionResult.h
index 333b305ec4..1577eb369d 100644
--- a/src/ifcgeom/ConversionResult.h
+++ b/src/ifcgeom/ConversionResult.h
@@ -245,14 +245,8 @@ namespace IfcGeom {
 		ConversionResult(int id, ConversionResultShape* shape)
 			: id(id), placement_(ifcopenshell::geometry::taxonomy::make<ifcopenshell::geometry::taxonomy::matrix4>()), shape_(shape)
 		{}
-		void append(ifcopenshell::geometry::taxonomy::matrix4::ptr trsf) {
-			// @todo verify order
-			placement_->components() = placement_->ccomponents() * trsf->ccomponents();
-		}
-		void prepend(ifcopenshell::geometry::taxonomy::matrix4::ptr trsf) {
-			// @todo verify order
-			placement_->components() = trsf->ccomponents() * placement_->ccomponents();
-		}
+		void append(ifcopenshell::geometry::taxonomy::matrix4::ptr trsf);
+		void prepend(ifcopenshell::geometry::taxonomy::matrix4::ptr trsf);
 		std::shared_ptr<ConversionResultShape> Shape() const { return shape_; }
 		ifcopenshell::geometry::taxonomy::matrix4::ptr Placement() const { return placement_; }
 		bool hasStyle() const { return !!style_; }