av = DBIS->get_fbav(imp_sth);
    num_fields = AvFILL(av)+1;

    /* XXX
       The code in the if() below is likely to break with new versions
       of DBI!!! */
    if(num_fields < imp_sth->numCols) {
	int isReadonly = SvREADONLY(av);
	if(isReadonly)
	    SvREADONLY_off(av);		/* DBI sets this readonly  */
	i = imp_sth->numCols - 1;
	while(i >= num_fields)
	    av_store(av, i--, newSV(0));
	num_fields = AvFILL(av)+1;
	if(isReadonly)
	    SvREADONLY_on(av);		/* protect against shift @$row etc */