update and concat

[Thomas McDonough]

I'm trying to set all the values of column 'map' to the value of column 
ML and '.png'.  My intuition and an extensive reading of the manual and 
mail archives tell me to do it like this:

mysql> update listings set map= concat (ML, '.png') where ML<>'';

but all I get is this:

ERROR 1064 (42000): You have an error in your SQL syntax; check the 
manual that corresponds to your MySQL server version for the right 
syntax to use near '(ML, '.png') where ML<>''' at line 1

What am I doing wrong?

Tom