How to center a rotation


I would like to know how to center a rotation point on a movieclip
I use

 myclip.rotation += 5;

but the movieclip rotates from its top left corner, which gives the impression it turns around some fixed point on the scene

I would like to make the movieclip rotate from its own center so that it doesn’t move around its corner.

I hope my question is clear enough for you

many thanks for your help