sqlplus column header misaligned

In wide sqlplus reports, column headers get misaligned from the data The code that led to this output was: set linesize 32767 set trimspool on col z format a1 alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss'; pro....+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8....+....9....+....0....+....1....+....2....+....3 select sysdate a, sysdate b, sysdate c, sysdate d, sysdate e, 'yyyyyyyyyyy' y, 'z' z from dual; select sysdate a, sysdate b, sysdate c, sysdate d, sysdate e, sysdate f, 'z' z from dual; How can this be fixed?