use File::Copy qw();
if (-f "Normalize.xsX") {
    print STDERR "Enabling XS in sources...\n";
    die "***** Failed, sources could be inconsistent! *****\n"
     unless File::Copy::move('MANIFEST',        'MANIFEST.N')
        and File::Copy::move('MANIFEST.X',      'MANIFEST')
        and File::Copy::move('Normalize.pm',    'Normalize.pmN')
        and File::Copy::move('Normalize.xsX',   'Normalize.xs')
        and File::Copy::move('Normalize.pmX',   'Normalize.pm');
}