diff --git a/src/Mod/Sandbox/Gui/AppSandboxGui.cpp b/src/Mod/Sandbox/Gui/AppSandboxGui.cpp
index 14664b6ae9..3fe70ad212 100644
--- a/src/Mod/Sandbox/Gui/AppSandboxGui.cpp
+++ b/src/Mod/Sandbox/Gui/AppSandboxGui.cpp
@@ -67,7 +67,7 @@ private:
     void slotChangedObject(const App::DocumentObject& Obj, const App::Property& Prop)
     {
 #ifdef HAVE_PART
-        if (object == &Obj && Prop.getTypeId() == Part::PropertyGeometryList::getClassTypeId()) {
+        if (object == &Obj && Prop.is<Part::PropertyGeometryList>()) {
             const Part::PropertyGeometryList& geom = static_cast<const Part::PropertyGeometryList&>(Prop);
             const std::vector<Part::Geometry*>& items = geom.getValues();
             if (items.size() != 2)