A thief who thought he had finagled free food became angry after realizing he had stolen empty pizza boxes, Guelph Police say.

The incident happened on Gordon Street, near the city’s downtown, around 2:30 a.m. Sunday.

According to police, a male pizza delivery driver was in his parked vehicle at that time when a man approached the vehicle and knocked on the passenger-side window.

After the driver opened the window, the man allegedly grabbed three pizza boxes and ran down the driveway of a nearby residence.

The driver left his vehicle to keep an eye on the man and allegedly saw him opening the boxes and discovering that none of them contained pizza.

Police say the man then became angry and charged at the driver, knocking him to the ground.

Officers responded and arrested the man a short distance away.

Mason Swift, an 18-year-old Guelph man, is charged with robbery.