0 - 1 of 1 tags for compare NULL

I have to select rows from the table where col1=max(col1).
Here if the max(col1) is null, i dont get results because NULL cannot be compared as far as i know.
Temporarily i have used COALESCE(COL1,CURRENT_DATE)= COALESCE(MAX(COL1),CURRENT_DATE) to fetch records.
Will this temp solution affect in terms of performance ?