Walmart apologized after a vendor described a product using a racial slur on the retailer’s website.

The unidentified vendor listed a netting weave cap for sale on Walmart’s website and described the item as “n****r brown,” reported the New York Post.

The racial slur was brought to Walmart’s attention on Twitter, where social media users asked the retailer for an explanation.

The same item, which is used to anchor hair extensions, is available for sale on Amazon, but doesn’t include a racial slur in the description.

Walmart promptly replaced the “add to cart” button with a message stating the item was no longer available.

The retailer explained that manufacturers and suppliers provide product descriptions, and that listing had not yet been verified by Walmart.

“We are very sorry and appalled that this third party seller listed their item with this description on our online marketplace,” spokeswoman Danit Marquardt wrote in a statement. “It is a clear violation of our policy, and has been removed, and we are investigating the seller to determine how this could have happened.”