-extern void LaTeXOptionsOK(FL_OBJECT *, long);
-extern void LaTeXOptionsApply(FL_OBJECT *, long);
-extern void LaTeXOptionsCancel(FL_OBJECT *, long);
+extern "C" void LaTeXOptionsOK(FL_OBJECT *, long);
+extern "C" void LaTeXOptionsApply(FL_OBJECT *, long);
+extern "C" void LaTeXOptionsCancel(FL_OBJECT *, long);