In its latest technical directive, the FIA have told Formula 1 teams that they will be allowed to mount rear-view mirrors on the Halo so long as they comply with relevant regulations.
Mirrors have become an issue this year with driver complaints about rear visibility with current wing regulations.
Some teams such as Ferrari have pushed their mirror design further, but only in the pursuit of increased aerodynamics by creating an air duct.
After inquiries from teams regarding the possibility of mounting mirrors on the Halo, the FIA's single-seater technical boss Nikolas Tombazis has clarified the governing body's position.
His latest directive has been reported by Motorsport, and he's said: "We expect that you will be able to satisfy us that the installation is sufficiently rigid to ensure that the mirror does not vibrate too much, which would limit driver visibility.
"We will not accept a dual mirror mounting (halo + traditional survival cell), as this could cause delays in the event a rescue team had to remove the halo following an accident.
"We will not accept a cable or connectors to run through the halo fairing, hence in the rare case when a team is asked to mount cameras in the mirrors (position 1 of Drawing 6 of the Technical Regulations), that team would have to resort in using a mirror installation on the chassis or side pod."
Mirrors will still have to meet all current regulations, including those that specify the "box" within which they have to be mounted is a minimum 150mm x 50mm.
They will also be subject to the rear vision test conducted by the FIA, in which a driver has to read letter or number boards placed behind the car.
Halo has at times proved controversial in F1, but this announcement will be warmly received by the teams with increased aerodynamic possibilities in the removal of side-mounted mirrors.
This certainly seems to be a case where the Halo is adding benefit to the job of the aerodynamacist as well as driver safety.