Thanks for your quick answer Robert. Sure it doesn't affect the program behaviour but the debug with Visual C++ IDE is little bit more painful ;-). I'm going to fix my own copy of the file. Marc Viala De la part de Robert Ramey clearly its a bug but it shouldn't affect any programs, I'll fix it in my working copy. You can fix it by just initializing to 0. Robert Ramey "Marc Viala" <mviala@acticm.com> wrote in message news:D0D608FD34E14C4BA93A30AC162651E18BA519@SERVEUR2003.acticm.com... I've downloaded recently the version Boost 1.34.1 and performed some tests on ours applications integrating Boost components. During theses tests, I've tried to deserialize some XML archives generated w/ Boost 1.33.1 including some boost::optional<> instances and I've observed that the Visual C++ 7.1 IDE emits run-time checks in the load<boost::optional<>>() @ line 60 in file boost/serialization/optional.hpp. template<class Archive, class T> void load( Archive & ar, boost::optional<T> & t, const unsigned int /*version*/ ){ bool tflag; ar >> boost::serialization::make_nvp("initialized", tflag); if (tflag){ unsigned int v; if(3 < ar.get_library_version()){ ar >> make_nvp("item_version", v); } detail::stack_construct<Archive, T> aux(ar, v); ^^^^^^^^^^^^^^^^^^^^^^^^ Here Run-Time Check Failure #3 - The variable 'v' is being used without being defined. ar >> boost::serialization::make_nvp("value", aux.reference()); t.reset(aux.reference()); } else { t.reset(); } } Is it possible to avoid this run-time check by a preinitialisation of the local variable "v"? Is it a Bug? Best regards, Used Configurations: Windows XP Boost 1.34.1 (through Boost Installer w/ DLL libraries) Marc Viala