I'm trying to build an extension that uses the \uxxxx characters, but building the library fails. The "Writing R Extensions" guide says that these characters should not be used, but I really can't find any way around them. Is there any way to configure the building of a library so that it will allow them to be used? I'm currently building and installing using the following code. R CMD build newpkg R CMD INSTALL GUIdemo_1.0.tar.gz If there is absolutely no way to include the escape characters then I may have to go a different way, but using \uxxxx seems to be the only way to include greek symbols in tcltk menus, so I would prefer to keep using them. Thanks, Sam