The German government is warning the nation’s Tesla owners about the dangers of putting too much trust in their cars’ Autopilot system.

Reuters reports that the German Transport Ministry has taken the step of sending a letter to all of them as a reminder that they are ultimately responsible for the operation of their vehicles, and that Autopilot is merely an assist system.

The feature, which can autonomously maintain the car’s speed, brake for obstacles, steer within a lane and even change lanes on command, became a point of controversy after a driver in Florida suffered a fatal crash while using it.

Tesla driver using Autopilot feature killed by tractor trailer

An internal report from the German Transport Ministry called it a “considerable traffic hazard," according to Der Spiegel.

Since launching it last year, Tesla has modified the way Autopilot operates, in part to prevent its misuse, by restricting how long and at what speeds drivers are able to remove their hands from the wheel.