Ok, this one is slightly unusual. On Friday, Lululemon filed a legal complaint against rival Under Armour for design patent infringement, according to Fashion Network.

The design patent in question? A bra strap, specifically a bra strap consisting of four criss-crossed panels of fabric.

“An ordinary observer will perceive the overall appearance of the designs of the infringing products to be substantially the same as the overall appearance of the designs of the patent-in-suit,” the claim reads.

This isn’t the first time Lululemon, which has collected more than 50 design patents to date, has gone after a rival for patent infringement. In 2012, the Vancouver-based athleisure company brought a patent suit against Calvin Klein for violating one of its yoga pants designs (the companies reached a confidential settlement).