Selecting distinct columns with MySQL

In the past I was sure it was not possible in MySQL to use DISTINCT on multiple columns, such as below;

SELECT DISTINCT a,b FROM my_table;

and have in the past, instead used something similar to the below as a workaround;

SELECT DISTINCT CONCAT (a,' ', b) FROM my_table;

However, it seems I am remiss and MySQL does indeed support DISTINCT on multiple columns.