Increasing on the Purl side

:knitting: I’m brand new to this website (as of 30 minutes ago!).
I am knitting a baby sweater and finished the front and back. The directions for the sleeves call for “increase 1 stitch at the beginning and end of every 4th row. Do this 9 times” I think the 4th row is a purl row. Can I increase on a purl row?

Any help is appreciated!

LuckyDog

Yes, you can do a purl front and back or M1 increase done purlwise.