Get free guacamole at Chipotle for National Avocado Day

(Photo by Joe Raedle/Getty Images)

Wednesday is National Avocado Day, and customers at Chipotle can get free guacamole to celebrate -- but there's a catch.

The restaurant chain says it won't charge extra for guac on July 31, but only for customers who place their orders online or from the Chipotle app.

The offer is good for one free topping of guacamole with the purchase of any regular-priced entree.

A scoop of guacamole usually costs around $2 at Chipotle.

LINK: For more details on the one-day-only deal, visit Chipotle's website.