diff --git a/Spatial_sorting/include/CGAL/Hilbert_sort_middle_2.h b/Spatial_sorting/include/CGAL/Hilbert_sort_middle_2.h
index 1d0d6b7792f..6160a7bea58 100644
--- a/Spatial_sorting/include/CGAL/Hilbert_sort_middle_2.h
+++ b/Spatial_sorting/include/CGAL/Hilbert_sort_middle_2.h
@@ -123,22 +123,20 @@ public:
   void operator() (RandomAccessIterator begin, RandomAccessIterator end) const
   {
     //Bbox_2 box=bbox_2(begin, end); BUG: WE NEED TO FIX THIS
-
-    K k;
-    double xmin=to_double(k.compute_x_2_object()(*begin)),
-           ymin=to_double(k.compute_y_2_object()(*begin)),
+    double xmin=to_double(_k.compute_x_2_object()(*begin)),
+           ymin=to_double(_k.compute_y_2_object()(*begin)),
            xmax=xmin,
            ymax=ymin;
 
     for(RandomAccessIterator it=begin+1; it<end; ++it){
-      if ( to_double(k.compute_x_2_object()(*it)) < xmin)
-        xmin = to_double(k.compute_x_2_object()(*it));
-      if ( to_double(k.compute_y_2_object()(*it)) < ymin)
-        ymin = to_double(k.compute_y_2_object()(*it));
-      if ( to_double(k.compute_x_2_object()(*it)) > xmax)
-        xmax = to_double(k.compute_x_2_object()(*it));
-      if ( to_double(k.compute_y_2_object()(*it)) > ymax)
-        ymax = to_double(k.compute_y_2_object()(*it));
+      if ( to_double(_k.compute_x_2_object()(*it)) < xmin)
+        xmin = to_double(_k.compute_x_2_object()(*it));
+      if ( to_double(_k.compute_y_2_object()(*it)) < ymin)
+        ymin = to_double(_k.compute_y_2_object()(*it));
+      if ( to_double(_k.compute_x_2_object()(*it)) > xmax)
+        xmax = to_double(_k.compute_x_2_object()(*it));
+      if ( to_double(_k.compute_y_2_object()(*it)) > ymax)
+        ymax = to_double(_k.compute_y_2_object()(*it));
     }
 
     sort <0, false, false> (begin, end, xmin, ymin, xmax, ymax);