Help with pattern and size needles

I would like to make this hat.

I just finished it, and because I am a tight knitter, it is a bit smaller than the size measured. So, I thought I would make it with 9mm this time–can I follow the pattern as stated, and just use a bigger needle?


that is a common method for making things a little larger without altering the pattern.

Yes, I agree with tarrentella. But I have to ask…Did you knit a gauge swatch? That would have told you what needles you needed to use on the first hat.