Strange output in Stats() keys

[Comradin]

Hello,

I use a simple loop to iterate over the keys and values of the map Stats() returns:

        stats, err := ethtool.Stats(device)
        if err != nil {
                panic(err)
        }

        for key, value := range stats {
                if strings.HasPrefix(key, "ptp_") {
                        fmt.Printf("Key: %v, Value: %v.\n", key, value)
                }
        }

But this results in output, that is filled with special characters like this:
Key: ptp_good_syncs���� Value: 76414806
Key: ptp_bad_syncs�q Value: 2
Key: ptp_non_filter_matches Value: 0
Key: ptp_invalid_sync_windows���K��� Value: 0
Key: ptp_filter_matches
���� Value: 0
Key: ptp_undersize_sync_windows��� Value: 22259
Key: ptp_no_time_syncs Value: 2
Key: ptp_oversize_sync_windows Value: 19631
Key: ptp_rx_timestamp_packets� Value: 0
Key: ptp_sync_timeouts Value: 20
Key: ptp_fast_syncs��cg�����pK����� Value: 74814754
Key: ptp_rx_no_timestamp Value: 0
Key: ptp_tx_timestamp_packets��8 Value: 70378
Key: ptp_timestamp_packetsa{U{UValue: 70378

or it looks like there are values in my string like this (withtout the HasPrefix() filtering
Key: tx-9.tx_packets2235 624160 1684 Value: 91028224
Key: tx-10.tx_packets0 0 0 0 0 0 0 0 Value: 101749747
Key: tx-19.tx_packets0 0 0 0 0 0 0 0 Value: 137001195
Key: tx-20.tx_packets0 0 0 0 0 0 0 0 Value: 103459984
Key: ptp_no_time_syncs 0 0 0 0 0 0 0 Value: 2

Any ideas on why this happens, am I doing something wrong?

Regards,
Marcus