Technology and automotive companies may see self-driving cars as the future of transportation, but many members of the public still aren’t won over by the idea, with safety issues being one of the main concerns. That fear might be compounded by a new report, which shows just how easy it is to confuse the cars.

Car and Driver notes how security researchers at the University of Washington found they could easily trick autonomous vehicles’ image recognition systems by defacing street signs. By adding the words ‘LOVE’ and ‘HATE’ to the sign above, the computer vision algorithm no longer recognized it as a stop sign and instead believed it to be a speed limit notice.

What’s worrying is the way some signs only needed slight modifications to throw off the cars’ algorithms. A Right Turn sign was created that looks very similar to the real thing, but the subtle alterations make it appear as a Speed Limit 45 sign to autonomous vehicles. The worst part is that these stickers could be made by anyone using a home printer.

The researchers did suggest solutions to the problem. Using contextual information is one answer; a car could be programmed to question why a stop sign is on a highway, or a high speed-limit warning on a back road. Additionally, information from other sensors, such as cameras, lidar, and GPS, could be taken into account when determining if a sign is real.

In late 2015, a research fellow at the University of Cork, Ireland, discovered a way of tricking self-driving cars into seeing phantom objects by using a home-made electronics kit costing less than $60.

Estimates say it’ll be another ten years or more before self-driving cars are a common sight on our roads, which should give manufacturers enough time to iron out the bugs. But the vehicles are unlikely to ever become popular in India; the country’s transport minister recently said he would protect human jobs by banning the technology.