The Facebook-PayPal relationship keeps getting friendlier.

The companies announced Tuesday that PayPal users can send invoices over Facebook Messenger, expanding a partnership announced last month that allowed Messenger users to link to their PayPal accounts for sending and receiving money.

The agreement is moving from peer-to-peer payments to include the buying and selling of products in Facebook’s marketplace. PayPal’s buyer protection is also available for transactions.

Sellers can create an invoice within Messenger and then send it to the buyer. This is available in the U.S., where PayPal has over 2.5 million accounts that are already linked to Facebook.

By partnering with PayPal, Facebook Messenger becomes a competitor to mobile payment services like Apple‘s new Pay Cash, Square Cash, Snap and PayPal’s own Venmo application.