Kim Kardashian is lashing out after a knockoff version of a one-of-a-kind vintage dress she wore over the weekend suddenly was up for sale on another site, and the model who wore the dress accidentally supported Kim's take.

Kim wore a black dress on Sunday night from famed designer Thierry Mugler’s vintage collection to the 5th Annual Hollywood Beauty Awards. After seeing the dress for sale online, KKW went on a massive Twitter rant, calling out the sites (presumably she's talking about Fashion Nova) and denying any relationship with them.

Kim Kardashian dress
Getty / Fashion Nova

"It’s devastating to see these fashion companies rip off designs that have taken the blood, sweat and tears of true designers who have put their all into their own original ideas," she began. "I’ve watched these companies profit off my husband’s work for years and now that it’s also affecting designers who have been so generous to give me access to their beautiful works, I can no longer sit silent."

She explained, "Only two days ago, I was privileged enough to wear a one-of-a-kind vintage Mugler dress and in less than 24 hours it was knocked off and thrown up on a site - but it's not for sale. You have to sign up for a waitlist because the dress hasn’t even been made to sell yet."

Kim Kardashian is seemingly referring to Fashion Nova, where the dress is listed as being "sold out" in all sizes.

Kim Kardashian dress
Fashion Nova

She claims the websites that do this "make people believe there is some kind of relationship between me and this fashion site. There is not."

Kim continued, "My relationships with designers are very important to me. It's taken me over a decade to build them and I have a huge amount of respect for the amount of work that they put into bringing their ideas to life."

She says she plans her looks for weeks and even months or a year in advance, saying she is "grateful for every fashion moment those designers and their dresses have helped me create."

Kim Kardashian concluded by saying, "So, as always, don’t believe everything you read and see online. I don’t have any relationships with these sites. I’m not leaking my looks to anyone, and I don’t support what these companies are doing."

The model who wore the dress for Fashion Nova posted a video to her Instagram Story last night, showing various snaps from the photo shoot. It's worth noting ... the file name says "Kim dress."

Kim Kardashian dress
Instagram

The Kardashians have a controversial relationship with Fashion Nova. Last year, the site had for sale several outfits worn by the sisters to Kylie Jenner's birthday party ... on the same day as the party.

The Blast reached out to Fashion Nova for comment — so far, no word back.