...
  eval {
    my $consts = Win32::OLE::Const->Load( "Microsoft Word" );
    my $msword = Win32::OLE->GetActiveObject('Word.Application') ||
                 Win32::OLE->new('Word.Application', 'Quit') ||
        die "cannot get or create word: $!";

    $msword->{Visible}       = 0;
    $msword->{DisplayAlerts} = $consts->{wdAlertsNone};
    $msword->Documents->OpenNoRepairDialog( $in_filename ) ||
      die "cannot open $in_filename - ", Win32::OLE->LastError();

    $msword->ActiveDocument->SaveAs( {
      FileName   => $out_filename,
      FileFormat => $consts->{wdFormatPDF},
    } );

    $msword->ActiveDocument->Close( 0 );
  };
  ...