BMW last week issued a stop-sale order and recall for every i3 in the United States, meaning from the 2014 model up to the present 2018 car. A total 30,542 cars are affected.

The cause? It seems that in a recent round of testing, the National Highway Traffic Safety Administration determined that a limit was exceeded in one particular case.

The limit concerns the case where a 5th-percentile women (about 5 feet tall and weighing between 100 and 110 pounds)  in the driver’s seat and not wearing a safety belt could have a marginally higher risk of a neck injury in certain frontal crashes.

InsideEVs obtained a document sent out to BMW dealers detailing the issue. In the document, BMW states that a fix is still being determined and that customers will be notified of the recall by mail starting in January, 2018.

In a statement, BMW said its own testing had shown the i3 met all safety standards. The automaker also said it was working with NHTSA to determine the discrepancy and come up with a remedy.

In its statement, BMW also said the i3 remains safe to drive, as long as you keep your safety belt on.