Lime has issued a warning to riders about a firmware bug in the company’s electric scooters that can cause “sudden excessive braking” during use, via The Washington Post.

The bug tends to occurs when riding downhill at top speed

According to Lime, the bug occurs in “very rare cases,” usually when a rider is going downhill at top speed and hits a pothole or obstacle, the scooter will unexpectedly brake the front wheel, which has led to some riders being injured. Lime says that the issue isn’t common, with less than 0.0045 percent of all Lime rides encountering the problem, but the company is warning customers anyway and noting that they should use extra caution while the issue is being fixed.

To that end, Lime has already started rolling out a preliminary update that the company says has cut down on issues already, and is actively working on a final fix that it hopes to have finished shortly.

Until that time, Lime recommends that riders test the brakes on any scooters they use at the start of the trip to make sure that they’re working properly, and to avoid going at top speed downhill until the final firmware patch has been completed.

Lime isn’t the only scooter company to have a recent braking scare; earlier in the month, a firmware vulnerability was found in the Xiaomi M365 electric scooter (which Lime does not use, but some rivals do) that could allow a hacker to remotely trigger the brakes on the scooters.