change line price to zero on invoiced line

For a priced PO line that has invoice dollars matched to it, if the user revised the PO to change the price of a line to $0 the system will display a warning message that states "You changed the price on a purchase order line that has been invoiced or received with accrued liability. These receipts and invoices won't be updated." Is there a way to make this warning message a hard stop validation error? We have users ignoring the message which is causing accounting issues.