It's no secret that images of models are often retouched to make their bodies look thinner or curvier in certain places, to lengthen their legs to mannequin-esque proportions, or to smooth out their skin and widen their eyes, reports the BBC.
From Sunday, in France, any commercial image that has been digitally altered to make a model look thinner will have a cigarette-packet style warning on it.
"Photographie retouchée", it will say, which translates to "edited photograph".
Anyone flouting the new rule could be fined €37,500 (£33,000) or 30% of the cost of creating the ad.
The government is essentially trying to tackle persistent image-doctoring as a public health issue.
It's hoped the change will help tackle extreme thinness among models, and body image problems among those who aspire to shapes they cannot hope to live up to because they were faked on a computer programme.
"Exposing young people to normative and unrealistic images of bodies leads to a sense of self-depreciation and poor self-esteem that can impact health-related behaviour," former health minister Marisol Touraine said.
France is not the first country to introduce these kinds of rules. Israel, for example, has already done so.
But thinness gets a lot of attention in France.
Tens of thousands of people in the country suffer from anorexia and the average body mass index (BMI) - a measure used to determine if someone is underweight or overweight - is the lowest in Europe.
In one new book, author Gabrielle Deydier makes the case that thinness is revered in her country, and fatness despised. She even lost her job in a school, she says, after a colleague took exception to her obesity. Another time, in a job interview, she was shocked to hear her interviewer say it was "well-known" that fatter people had lower IQs.