I should have also included the error:

In file included from /usr/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/../../../../include/g++-3/stl_tree.h:56, from /usr/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/../../../../include/g++-3/set:31, from ../maildir/maildirkeywords.h:435, from maildir.C:28: /usr/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/../../../../include/g++-3/stl_algobase.h:91: `template <class _Tp> const _Tp & min(const _Tp &, const _Tp &)' redeclared as different kind of symbol mio.h:80: previous declaration of `class MioStdio min' mio.h:80: previous non-function declaration `class MioStdio min' /usr/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/../../../../include/g++-3/stl_algobase.h:91: conflicts with function declaration `template <class _Tp> const _Tp & min(const _Tp &, const _Tp &)' /usr/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/../../../../include/g++-3/stl_algobase.h:103: `template <class _Tp, class _Compare> const _Tp & min(const _Tp &, const _Tp &, _Compare)' redeclared as different kind of symbol mio.h:80: previous declaration of `class MioStdio min' mio.h:80: previous non-function declaration `class MioStdio min' /usr/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/../../../../include/g++-3/stl_algobase.h:103: conflicts with function declaration `template <class _Tp, class _Compare> const _Tp & min(const _Tp &, const _Tp &, _Compare)' /usr/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/../../../../include/g++-3/stl_algobase.h: In function `bool lexicographical_compare(const unsigned char *, const unsigned char *, const unsigned char *, const unsigned char *)': /usr/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/../../../../include/g++-3/stl_algobase.h:442: no match for call to `(MioStdio) (const size_t &, const size_t &)' /usr/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/../../../../include/g++-3/stl_algobase.h: In function `int __lexicographical_compare_3way(const unsigned char *, const unsigned char *, const unsigned char *, const unsigned char *)': /usr/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/../../../../include/g++-3/stl_algobase.h:490: no match for call to `(MioStdio) (const ptrdiff_t &, const ptrdiff_t &)' make[2]: *** [maildir.o] Error 1 make[2]: Leaving directory `/usr/src/maildrop-1.6.1/maildrop' make[1]: *** [all] Error 2 make[1]: Leaving directory `/usr/src/maildrop-1.6.1/maildrop' make: *** [all-recursive] Error 1