Vending machines at a university in Canada are to be removed amid privacy concerns after students discovered they were apparently secretly using facial recognition technology, CTV News reported Friday.

Students noted that one of the machines that was selling candy at the University of Waterloo near Toronto was displaying a message, saying that an application error had occurred with facial recognition.

“We wouldn’t have known if it weren’t for the application error. There’s no warning here,” River Stanley, a student, who investigated the machines for an article in a university publication, told CTV.

The university said it would remove the vending machines “as soon as possible.”

In the meantime, students have been sticking gum over the sensors on the machine.

The manufacturer of the machines, Invenda, denied it was storing or transmitting information.

The company acknowledged to the school paper mathNEWS that it used “demographic detection software” in the machines, but said it operates “entirely locally.”

“It does not engage in storage, communication, or transmission of any imagery or personally identifiable information,” Invenda said.

CTV quoted Invenda’s website as saying that the Smart Vending Machines can detect the presence of a person, their estimated age and gender. The website said the “software conducts local processing of digital image maps derived from the USB optical sensor in real-time, without storing such data on permanent memory mediums or transmitting it over the Internet to the Cloud.”

Invenda said the software is compliant with the European Union privacy law General Data Protection Regulation.

The rise of cloud computing and AI technologies have popularized the use of facial recognition globally, from tracking criminals to unlocking smartphones.

But as cameras appear at unlikely spots across the globe, activists raise fears about lost privacy and say society might be on the doorstep of a dystopia where Big Brother sees all.

Agencies contributed to this report.