Hi, I am not much of a Windows programmer, so I have a basic question. I want to make a library that (among other stuff) defines an exception like this: #include <boost/exception/exception.hpp> namespace speedo { typedef boost::error_info<struct tag_error, unsigned> error_info; class __declspec(dllexport) exception : public boost::exception { }; } When I try to compile this, I get the following warning: c:\cygwin\home\andrej\speedo\trunk\util\exception.h(14) : warning C4275: non dll-interface class 'boost::exception' used as base for dll-interface class 'speedo::exception' C:\cygwin\home\Andrej\speedo\trunk\boost/exception/exception.hpp(47) : see declaration of 'boost::exception' c:\cygwin\home\andrej\speedo\trunk\util\exception.h(13) : see declaration of 'speedo::exception' Is this a problem, and, how do I get rid of this without changing the boost-exception lib itself? Cheers, Andrej __________________________________________________________ Not happy with your email address?. Get the one you really want - millions of new email addresses available now at Yahoo! http://uk.docs.yahoo.com/ymail/new.html