How do we provide file name in GZip in express(nodejs)?

The below code works fine and I am able to download file in Zip formant but it downloads the file as download_log.zip. How can I give a meaningful name of the file?

    exports.download = function(req,res){   
        var gzip = zlib.createGzip();
        var rstream = fs.createReadStream(filePath);
        rstream.pipe(gzip).pipe(res);

}