NASCAR’s governing body has become interested in what the sport’s drivers are wearing under it all. The sport made modifications to the rule book to mandate that drivers wear fireproof underwear, socks, and more.

The updates are being made for a very good reason, that being the safety of the drivers, who may have already been wearing the gear. NASCAR’s governing body modified the rule book this week to make fire-resistant head socks and/or helmet skirts, underwear, and socks a requirement for drivers, rather than a recommendation.

It’s unclear why this particular moment was chosen to make the undergarments a requirement rather than a suggestion, but follows tightening regulations in other motorsports. Formula One, for instance, introduced stricter rules about what jewelry and underwear the drivers could wear following driver Romain Grosjean’s narrow escape from a fireball after a big crash in 2020.

Read: Drifting Ford Mustang Literally Takes The Pants Off From Sideshow Spectator

In NASCAR, meanwhile, fans mostly seem mystified that the protective gear wasn’t already a requirement. Among the few complaints, one fan worried that the new rule would prevent drivers from wearing “cool t-shirts under suits,” though it’s unlikely that this ruling would not actually prevent that from happening.

Others wondered if the rule change was a response to an incident that took place at Talladega last year in the NASCAR Truck Series. That incident saw Jordan Anderson’s race truck engulfed in flames while the car was traveling at full speed down the track. The driver survived, but suffered third-degree burns in the incident.

Most fans, though, simply wondered how NASCAR would ensure that the drivers are wearing their undergarments, and made light-hearted comments about the idea. Even other brands got in on the fun, with sim racing game iRacing saying that fireproof underwear was still optional in its races.