diff --git a/Surface_mesh/include/CGAL/Surface_mesh/Surface_mesh.h b/Surface_mesh/include/CGAL/Surface_mesh/Surface_mesh.h
index b7b1f359e36..8ce4c1e13f9 100644
--- a/Surface_mesh/include/CGAL/Surface_mesh/Surface_mesh.h
+++ b/Surface_mesh/include/CGAL/Surface_mesh/Surface_mesh.h
@@ -123,9 +123,7 @@ namespace CGAL {
         /// decrement.
         SM_Index operator--(int) { SM_Index tmp(*this); --idx_; return tmp; }
 
-
-      
-     
+        SM_Index operator+=(std::ptrdiff_t n) { idx_ += n; return *this; }
       
     private:
         size_type idx_;
@@ -463,12 +461,12 @@ private: //------------------------------------------------------ iterator types
     class Index_iterator
       : public boost::iterator_facade< Index_iterator<Index_>,
                                        Index_,
-                                       std::bidirectional_iterator_tag
+                                       std::random_access_iterator_tag
                                        >
     {
         typedef boost::iterator_facade< Index_iterator<Index_>,
                                         Index_,
-                                        std::bidirectional_iterator_tag
+                                        std::random_access_iterator_tag
                                         > Facade;
     public:
         Index_iterator() : hnd_(), mesh_(NULL) {}
@@ -497,6 +495,18 @@ private: //------------------------------------------------------ iterator types
                while ( mesh_->has_valid_index(hnd_) && mesh_->is_removed(hnd_)) --hnd_;
         }
 
+        void advance(std::ptrdiff_t n)
+        {
+            CGAL_assertion(mesh_ != NULL);
+            CGAL_assertion(!(mesh_->has_garbage()));
+            hnd_ += n;
+        }
+
+        std::ptrdiff_t distance_to(const Index_iterator& other) const
+        {
+          return std::ptrdiff_t(other.hnd_) - std::ptrdiff_t(this->hnd_);
+        }
+      
         bool equal(const Index_iterator& other) const
         {
             return this->hnd_ == other.hnd_;