Versuch mal ca. Zeile 672 (hinter check_last() )

die if Abfage würde bei Null Daten (numnibbles=0) zurückspringen.

Code:
       if (!rx->numnibbles) return; 

        clean_temp(&s->l2.pocsag.temp);

        for (i = 0; i < 7; i++) {
                j = (rx->adr / pow(10,i));
                set[6 - i] = j - (j / 10) * 10;
        }

        memset(message,  0, sizeof(message));
        memset(func,     0, sizeof(func));
        memset(outprint, 0, sizeof(outprint));
        memset(alias,    0, sizeof(alias));

        /*      Datenzeile      */
        if (rx->func == 3 && rx->adr >= 4000 && rx->adr <= 5000)
                print_msg_skyper(rx, message, ctrl);
        else print_msg_alpha(rx, message, ctrl);