diff --git a/Linear_cell_complex/demo/Linear_cell_complex/Viewer.cpp b/Linear_cell_complex/demo/Linear_cell_complex/Viewer.cpp
index 3f82a3ffab7..dafcccb1695 100644
--- a/Linear_cell_complex/demo/Linear_cell_complex/Viewer.cpp
+++ b/Linear_cell_complex/demo/Linear_cell_complex/Viewer.cpp
@@ -15,7 +15,7 @@
 #include <CGAL/Qt/vec.h>
 
 Viewer::Viewer(QWidget* parent) :
-    Base(parent, NULL, ""),
+    Base(parent, nullptr, ""),
     m_previous_scene_empty(true)
 {}
 
@@ -50,4 +50,3 @@ void Viewer::keyPressEvent(QKeyEvent *e)
 
 QString Viewer::helpString() const
 { return Base::helpString("LCC Demo"); }
-
diff --git a/Linear_cell_complex/include/CGAL/draw_linear_cell_complex.h b/Linear_cell_complex/include/CGAL/draw_linear_cell_complex.h
index 6f630b2c0b1..ea7a8e07dfe 100644
--- a/Linear_cell_complex/include/CGAL/draw_linear_cell_complex.h
+++ b/Linear_cell_complex/include/CGAL/draw_linear_cell_complex.h
@@ -170,13 +170,17 @@ public:
     // First draw: vertices; edges, faces; multi-color; inverse normal
     Base(parent, title, true, true, true, false, false),
     lcc(alcc),
-    m_oriented_mark(lcc->get_new_mark()),
+    m_oriented_mark(LCC::INVALID_MARK),
     m_nofaces(anofaces),
     m_random_face_color(false),
     m_drawing_functor(drawing_functor)
   {
-    lcc->orient(m_oriented_mark);
-    compute_elements();
+    if (lcc!=nullptr)
+    {
+      lcc->get_new_mark();
+      lcc->orient(m_oriented_mark);
+      compute_elements();
+    }
   }
 
   ~SimpleLCCViewerQt()
@@ -185,14 +189,20 @@ public:
 protected:
   void set_lcc(const LCC* alcc, bool doredraw=true)
   {
+    if (lcc==alcc)
+    { return; }
+
     if (lcc!=nullptr)
     { lcc->free_mark(m_oriented_mark); }
 
     lcc=alcc;
-    m_oriented_mark=lcc->get_new_mark();
-    lcc->orient(m_oriented_mark);
+    if (lcc!=nullptr)
+    {
+      m_oriented_mark=lcc->get_new_mark();
+      lcc->orient(m_oriented_mark);
+      compute_elements();
+    }
 
-    compute_elements();
     if (doredraw) { redraw(); }
   }