Knock-offs have long been the bane of the fashion industry. One need only visit Canal Street in Manhattan to see “solid gold watches” peddled on the sidewalk, and Versace imitation purses hawked on the cheap. No brand wants to see a copy of their designer label sold on the black market. And no buyer wants to discover that their Rolex is really a faux-lex.

Unfortunately, knock-offs aren’t confined to the fashion industry. The reselling of long-tail inventory under fraudulent terms has become common practice in the digital advertising world. With the video market flush, and profit margins high, a ‘black market’ of long-tail inventory has emerged, filled with posers hawking resold ads under misrepresented terms. This particularly shady crew of ad agencies, SSPs and exchanges pose as direct partners of brands, taking their second-tier inventory and reselling it as premier content: essentially sucking dollars from the ecosystem without adding any inherent value.

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This is a problem for the entire supply chain. No publisher wants imitators siphoning off ad dollars by hawking their inventory, and no advertiser wants to waste money on a counterfeit; they want to reach real audiences and reward publishers directly for their original content. For buyers, resold inventory isn’t brand-safe and worse, can even cheapen brand value.

So how do we stop uncertified sellers and bootleggers from peddling counterfeit inventory and trying to pass it off as the real deal? How do we ensure publishers and their authorized partners are fairly compensated for their inventory, and that advertisers get what they pay for?

That’s where having a single, industry-wide source of truth would make it a lot harder for bad actors to fool advertisers with fake impressions and cheat publishers out of money.

Enter Ads.txt.

Aimed to help ad buyers avoid illegitimate sellers who arbitrage inventory and spoof domains, Ads.txt is a way for companies to list their legitimate partners. Essentially, it’s the ultimate whitelist: it shows all of a company’s direct relationships and certified sellers.

What’s more, is it puts power back into the hands of the content owners and distributors by giving them a simple and secure way to declare who is authorized to sell their inventory. No longer can indirect sellers pose as direct or official partners: they’re not on the list. Suddenly, a buyer knows whether they’re dealing with an authorized seller or the shady hawker guy on the corner in a trench coat. No name, no game.

Ads.txt is something the media supply chain should rally behind. The additional transparency it provides will give advertisers and programmatic buyers a means to validate authentic media sources in real-time and ensure media spend reaches legitimate and deserving publishers. It’s a no-B.S. way to detect if you’re buying real quality from a trusted partner or a cheap knockoff.

Supporting Ads.txt would also be a step towards digital’s shared goal of bringing transparency to what Procter & Gamble’s Marc Pritchard called the “crappy media supply chain.” If embraced, Ads.txt can clean up the entire ecosystem by bringing back trust among legitimate partners and approved sources so we can more effectively do business.

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Cleaning up digital video and ensuring ad dollars get in the right hands is especially important; if digital video is big, it’s only getting bigger. eMarketer expects US digital video ad spending will see double-digit growth annually through 2020. If we can prevent bad actors from siphoning off value, we all stand much to win. Even better, by supporting ads.txt, you’ll never be caught doing business with an imitator. Because ultimately, the only thing worse than a vendor selling the bootleg gold watches are the people who bought them and thought they were real.