Britain’s popular clothing retailers ASOS, Boohoo and George at Asda signed formal pledges on Wednesday at the instance of the regulator to ensure they only make green claims when they are accurate and conveyed clearly.

The Competition and Markets Authority (CMA) is attempting to crack down on greenwashing in the fashion industry, which is responsible for a notoriously high proportion of the world’s carbon emissions.   

These three retailers collectively generate £4.4 billion ($5.55 billion) in annual sales in the U.K., and will now tweak how they display and promote green credentials to ensure environmental benefits, if any, aren’t misrepresented. 

This could mean limiting the use of ambiguous terms like “eco” and “sustainable” when referring to different fabrics, and more clear messaging around whether materials are organic or recycled, the CMA said on Wednesday.

The move underscores how rampant greenwashing is within fashion and sets a precedent for other brands to follow. The British regulator has been investigating green claims made by the three retailers for close to two years now.

CEO Sarah Cardell said the agreement was a “turning point for the industry” and that “the sector as a whole” should revisit their practices. 

Shoppers are becoming increasingly aware of the environmental impact of fast fashion, prompting them to turn to brands that offer cleaner, more climate-friendly alternatives. However, several prominent fashion houses have come under fire for making pompous green claims to lure climate-conscious shoppers, even if they aren’t entirely true. 

Take H&M, for instance. Its “Conscious Collection” line of clothing says it’s better for the environment but has been scrutinized by European regulators for being misleading with its claims. 

To be sure, concerns surrounding the environmental footprint of the industry stretch beyond sustainability claims—companies are also trying to tackle textile waste that ends up in landfills. 

It could take decades before the fashion industry achieves tangible progress in slashing its environmental impact. However, curbing greenwashing practices could be the first step to eventually getting there.      

An Asda spokesperson told Fortune in a statement that it was “proactively engaged with CMA” and was “pleased” to have reached a voluntary agreement.

Representatives at Boohoo and ASOS didn’t immediately return Fortune’s request for comment.