Low-cost airline Norwegian Air has told its female staff that they must carry a doctor's note at all times if they want to wear flat shoes.
The controversial clause is featured in the company's new 22-page dress code, which states female workers must wear at least 2cm heels at all times while at work.
Those who decide to get the doctor's note will have to renew it every six months.
“It is almost comical that we face these issues in 2019,” Ingrid Hodnebo, a women's spokesperson for the country's Socialist Left Party, told Norwegian newspapers.
“While the rest of society has moved further, Norwegian sits firmly in the ‘Mad Men' universe from the 50s and 60s.”
Another eye-catching clause in Norwegian's new company regulations is that male employees are not allowed to wear make-up, with the exception of concealer to hide acne or bruises.
Their hair can't be any longer than shoulder length and they can't wear earrings.
Female employees on the other hands are expected to use eye make-up, light foundation and tinted moisturers or powders. They're allowed to use fake eyelashes, as long as they don't look fake.
Their jewellery is also under strict scrutiny: they can only wear two rings on every hand but none on their thumbs, and the only colour choices allowed are gold or silver.
Norwegian has defended itself by arguing that their uniform regulations are not too different from any other airlines and that their aim was to offer more specific information for their staff to avoid any confusion.
“Norwegian's crew must follow the company's uniform policy,” company spokesperson Astrid Mannion-Gibson told Norwegian news outlet VG.
“The uniform is neutral and discreet and yes, it does place different requirements on men and women when it comes to makeup, hair and so on. This is common among other airlines too.”