AC_REQUIRE([AC_FUNC_ALLOCA])dnl
AC_REQUIRE([AC_TYPE_MBSTATE_T])dnl
AC_CHECK_DECLS([getenv])
-AC_CHECK_FUNCS([mbsrtowcs mempcpy wmempcpy])
+AC_CHECK_FUNCS([btowc mbsrtowcs mempcpy wmempcpy])
AC_CHECK_HEADERS([wchar.h wctype.h])
AC_LIBOBJ([fnmatch])
AC_CONFIG_LINKS([lib/fnmatch.h:lib/fnmatch_.h])