Abstract: This relates to an improvement in a lock for closure panels of a carton of a wrap around type. Most specifically, the lock is formed between a male panel and a female panel of an overall closure panel with the male panel being provided with a projecting tab and the female panel having a folded down terminal panel portion with a cutout therein which receives the tab. With the lock so partially formed, scores or creases are rolled into the tab after which the tab is first folded down alongside the terminal panel portion of the female panel and then the folding of the tab is continued so as to swing the terminal female panel portion up beneath the male panel with a nose of the projecting tab passing through a slot in the male panel.