diff --git a/STL_Extension/include/CGAL/Compact_container.h b/STL_Extension/include/CGAL/Compact_container.h
index b4960af00c4..6064a81c6d9 100644
--- a/STL_Extension/include/CGAL/Compact_container.h
+++ b/STL_Extension/include/CGAL/Compact_container.h
@@ -28,6 +28,7 @@
 #include <CGAL/Default.h>
 
 #include <cmath>
+#include <cstddef>
 #include <iterator>
 #include <algorithm>
 #include <vector>
@@ -815,7 +816,8 @@ private:
 
   static char * clean_pointer(char * p)
   {
-    return ((p - (char *) NULL) & ~ (std::ptrdiff_t) START_END) + (char *) NULL;
+    return reinterpret_cast<char*>(reinterpret_cast<std::ptrdiff_t>(p) &
+                                   ~ (std::ptrdiff_t) START_END);
   }
 
   // Returns the pointee, cleaned up from the squatted bits.
@@ -828,7 +830,8 @@ private:
   static Type type(const_pointer ptr)
   {
     char * p = (char *) Traits::pointer(*ptr);
-    return (Type) (p - clean_pointer(p));
+    return (Type) (reinterpret_cast<std::ptrdiff_t>(p) -
+                   reinterpret_cast<std::ptrdiff_t>(clean_pointer(p)));
   }
 
   // Sets the pointer part and the type of the pointee.
@@ -837,7 +840,8 @@ private:
     // This out of range compare is always true and causes lots of
     // unnecessary warnings.
     // CGAL_precondition(0 <= t && t < 4);
-    Traits::pointer(*ptr) = (void *) ((clean_pointer((char *) p)) + (int) t);
+    Traits::pointer(*ptr) = reinterpret_cast<void *>
+      (reinterpret_cast<std::ptrdiff_t>(clean_pointer((char *) p)) + (int) t);
   }
 
 public: