diff --git a/Operations_on_polyhedra/include/CGAL/intersection_of_Polyhedra_3_refinement_visitor.h b/Operations_on_polyhedra/include/CGAL/intersection_of_Polyhedra_3_refinement_visitor.h
index f609e5b72ee..faf5f460bb5 100644
--- a/Operations_on_polyhedra/include/CGAL/intersection_of_Polyhedra_3_refinement_visitor.h
+++ b/Operations_on_polyhedra/include/CGAL/intersection_of_Polyhedra_3_refinement_visitor.h
@@ -1855,8 +1855,9 @@ public:
     
     internal_IOP::Non_intersection_halfedge<Polyhedron> criterium(border_halfedges);
 
-    int mark_index=final_map().get_new_mark(); //mark used to tag dart that are on an intersection
-    
+    int mark_index = static_cast<int>(final_map().get_new_mark());
+                     //mark used to tag dart that are on an intersection
+
     //define a map that will contain the correspondance between selected halfedges of the boundary and
     //their corresponding Dart_handle in the cmap.
     typedef std::map<Halfedge_const_handle,typename Combinatorial_map_3::Dart_handle,internal_IOP::Compare_address<Polyhedron> > Halfedge_to_dart_map;
diff --git a/Polyhedron/demo/Polyhedron/Polyhedron_demo_point_set_shape_detection_plugin.cpp b/Polyhedron/demo/Polyhedron/Polyhedron_demo_point_set_shape_detection_plugin.cpp
index 42f50edc8af..2c3546ec739 100644
--- a/Polyhedron/demo/Polyhedron/Polyhedron_demo_point_set_shape_detection_plugin.cpp
+++ b/Polyhedron/demo/Polyhedron/Polyhedron_demo_point_set_shape_detection_plugin.cpp
@@ -283,7 +283,7 @@ void Polyhedron_demo_point_set_shape_detection_plugin::build_alpha_shape
       if (ashape.classify (it) != Alpha_shape_2::INTERIOR)
         continue;
 
-      for (std::size_t i = 0; i < 3; ++ i)
+      for (int i = 0; i < 3; ++ i)
         {
           if (map_v2i.find (it->vertex (i)) == map_v2i.end ())
             {
diff --git a/Polyhedron/demo/Polyhedron/Scene_combinatorial_map_item.cpp b/Polyhedron/demo/Polyhedron/Scene_combinatorial_map_item.cpp
index 405450829b1..3e480295576 100644
--- a/Polyhedron/demo/Polyhedron/Scene_combinatorial_map_item.cpp
+++ b/Polyhedron/demo/Polyhedron/Scene_combinatorial_map_item.cpp
@@ -236,8 +236,10 @@ void Scene_combinatorial_map_item::compute_elements(void) const{
     //Facets
     {
     std::size_t index = 0;
-    int voltreated = combinatorial_map().get_new_mark();
-    int facetreated = combinatorial_map().get_new_mark();
+    Combinatorial_map_3::size_type voltreated
+      = combinatorial_map().get_new_mark();
+    Combinatorial_map_3::size_type facetreated
+      = combinatorial_map().get_new_mark();
     Combinatorial_map_3::Dart_const_range::const_iterator
             darts_it=combinatorial_map().darts().begin(), darts_end=combinatorial_map().darts().end();
     for( ; darts_it!=darts_end; ++darts_it)