Run a function on customer registration

Hi,

I am trying to run a function when a user registers on a site. It works perfectly when I register someone manually in the backend, but not when someone registers themselves through the WooCommerce checkout process.

Here’s the outline:

function do_something_on_registration($user_id) {
	// do stuff
}
add_action( 'user_register', 'do_something_on_registration', 10, 1 ); 

Is there another hook I should be using in this context rather than user_register?

Thanks for your time!