diff --git a/Polyhedron/demo/Polyhedron/Scene_polylines_item.cpp b/Polyhedron/demo/Polyhedron/Scene_polylines_item.cpp
index 83293052539..c9e8b3de7c5 100644
--- a/Polyhedron/demo/Polyhedron/Scene_polylines_item.cpp
+++ b/Polyhedron/demo/Polyhedron/Scene_polylines_item.cpp
@@ -435,7 +435,7 @@ void Scene_polylines_item::invalidateOpenGLBuffers()
 
 void Scene_polylines_item::change_corner_radii() {
     bool ok = true;
-    double proposed_radius = d->spheres_drawn_square_radius;
+    double proposed_radius = std::sqrt(d->spheres_drawn_square_radius);
     if(proposed_radius == 0) {
         CGAL::Three::Scene_interface::Bbox b = bbox();
         proposed_radius = (std::max)(b.xmax() - b.xmin(),