Reference warning in theme.inc line 617, solution proposal

When clicking on Checkout in the Cart, 2 warnings are flagged:

* warning: Parameter 1 to theme_ec_mail_checkout_form() expected to be a reference, value given in C:\xampp\xampp\htdocs\dp_cms\includes\theme.inc on line 617.
* warning: Parameter 1 to theme_ec_checkout_checkout_review_form() expected to be a reference, value given in C:\xampp\xampp\htdocs\dp_cms\includes\theme.inc on line 617.

Node http://drupal.org/node/613480 suggests this is caused by an & that should be removed.

Patching these files solves this warning:
ec_customer.theme.inc line 53
- function theme_ec_mail_checkout_form(&$form) {
+ function theme_ec_mail_checkout_form($form) {

ec_checkout.theme.inc lin 9
- function theme_ec_checkout_checkout_review_form(&$form) {
+ function theme_ec_checkout_checkout_review_form($form) {

I did not check the other function calls in the ec_xxx.theme.inc files, might as well that those need to be fixed too.

Hopefully this helps other users to solve the problem.

Configuration info:
Drupal 6.14
MySQL database 5.1.37
PHP 5.3.0
eCommerce 6.x-4.x-dev