Summer camp is that time-honored way of off-loading your children during the warmer months, leaving parents to enjoy their summer Fridays in peace and quiet. Eventually, though, parents may start to miss their offspring, and instead of waiting for a letter, they turn to the camp’s website for pictures of their kids having fun.

This year, summer camps have a new trick that makes it easier to find kids on camp websites—facial recognition. More than 100 summer camps have signed up to use facial recognition technology to help those bill-paying parents catch a glimpse of their precious child while they’re away at camp, according to the Asheville Citizen-Times. While parents may appreciate the chance to see their kids, the practice is making some privacy advocates nervous about the normalization of surveillance tech.

The camps reportedly all signed up for the program by VC-backed Waldo Photos (as in Where’s Waldo?). Parents upload a headshot or selfie of their kid using a private code. When the camp posts photos of happy campers on its website, Waldo’s face-recognition software scans the images. Then when it finds matches, it texts the photos to the child’s eager parents. Families who don’t sign up for the service have to scroll through photos the old-fashioned way.

While parents may love the service, privacy watchdogs are less impressed with the spread of what the ACLU has called an “invasive and error-prone technology” that can “pose serious privacy and safety risks.” Facebook recently changed its facial recognition photo tagging settings to address privacy concerns, and the FTC came out with a new set of suggested guidelines outlining several “best practices” for facial recognition technology.