Hello, boost::reverse_iterator::dereference() is typename super_t::reference dereference() const { return *boost::prior(this->base()); } boost::constant_iterator<T>::reference_type is T const&. So reverse_iterator< constant_iterator<T> >::dereference returns a reference to a temporary variable. Not good. I suggest removing the reference from boost::constant_iterator::reference_type, making it T. The rule would be that reference_type must only be a reference if the reference is pointing to some underlying container, not to the iterator itself. Arno -- Dr. Arno Schoedl · aschoedl@think-cell.com Technical Director think-cell Software GmbH · Chausseestr. 8/E · 10115 Berlin, Germany http://www.think-cell.com · phone +49 30 666473-10 · toll-free (US) +1 800 891 8091 Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl · Amtsgericht Berlin-Charlottenburg, HRB 85229