diff --git a/Partition_2/demo/Partition_2/partition_2.cpp b/Partition_2/demo/Partition_2/partition_2.cpp
index 433b3a77b2d..387bf93fc2c 100644
--- a/Partition_2/demo/Partition_2/partition_2.cpp
+++ b/Partition_2/demo/Partition_2/partition_2.cpp
@@ -157,10 +157,9 @@ private slots:
 
   void get_new_object(CGAL::Object obj)
   {
-    Cgal_Polygon poly;
-    if (CGAL::assign(poly, obj))
+    if (const Cgal_Polygon *poly = CGAL::object_cast<Cgal_Polygon>(&obj))
     {
-      polygon = poly;
+      polygon = *poly;
       something_changed();
     }
     widget->redraw();
diff --git a/Polygon/demo/Polygon/polygon_2.cpp b/Polygon/demo/Polygon/polygon_2.cpp
index 89adf417041..0c4575e64be 100644
--- a/Polygon/demo/Polygon/polygon_2.cpp
+++ b/Polygon/demo/Polygon/polygon_2.cpp
@@ -191,14 +191,12 @@ private slots:
 
   void get_new_object(CGAL::Object obj)
   {
-    Cgal_Polygon poly;
-    Point_2 p;
-    if(CGAL::assign(poly, obj)) {
-      polygon = poly;
+    if(const Cgal_Polygon *poly = CGAL::object_cast<Cgal_Polygon>(&obj)) {
+      polygon = *poly;
       something_changed();
       show_info();
-    } else if(CGAL::assign(p, obj)) {
-      point = p;
+    } else if(const Point_2 *p = CGAL::object_cast<Point_2>(&obj)) {
+      point = *p;
       is_point_visible = true;
       show_pinfo();
       something_changed();