Food startup Hampton Creek has received a warning letter from the Food and Drug Administration claiming the company’s Just Mayo products are “misbranded” because they do not meet the definition and standard of identify for mayonnaise.

The letter states that not only does the product lack eggs, a requirement under the legal definition of mayonnaise, but it also includes ingredients not permitted in the condiment: modified food starch, pea protein, and beta-carotene.

“We’re going to be sitting down and working collaboratively with the FDA to find common ground on this,” Hampton Creek CEO Josh Tetrick told Fortune, adding that he had a conversation with the agency earlier today. “We’re going to be responding to the letter thoughtfully and honestly.”

One critic of “big food” says the FDA is missing the point. “There is innovation happening here and unfortunately, it’s looking like the FDA isn’t quite keeping up with the innovation,” says Michele Simon, a public health lawyer. “It’s a shame because the last thing we need is hindrance in the marketplace, especially at a time when we’re facing a dramatic egg shortage.”

This is not the first time that Hampton Creek has been under fire for the ingredients in Just Mayo.

Last fall, Unilever filed a civil action against the startup, alleging false advertising and unfair competition because of Just Mayo’s lack of eggs. Hampton Creek’s Just Mayo competes with Unilever’s Hellmann’s brands, and the claim noted that Just Mayo was stealing market share from Hellmann’s. Unilever, which was criticized for taking on the pipsqueak rival, ended up dropping the lawsuit.

“We feel good about the name and that we’re following the appropriate policies here,” Tetrick told Fortune today. “That’s part of the reason why Unilever opted to withdraw the lawsuit. That was in some ways validation.”

Unilever declined to comment for this story.

At the time of the Unilever suit, Tetrick told Fortune that he did not think the company was in violation of the standard of identity. He added, “This is a conversation around how this system of food needs to be rethought. You’ve got to make it easier for innovators to innovate and for people to eat in a way that’s ultimately better.”

He also said that that the company was likely to be the target of other lawsuits as it branched into new products. “It’s just kind of the nature of change,” he told Fortune.

As we wrote then:

Vegan products branded as mayo that pre-date Hampton Creek are on the market, but those offerings are more clearly targeting health-conscious consumers. Tetrick has made a point of going after a larger demographic with Just Mayo, selling his product not just in the Whole Foods of the world but also the Wal-Marts. The company has historically downplayed that Just Mayo is vegan in order to appeal to a broader population. That also makes the product more of a direct threat to Unilever.

The letter from the FDA also said that the total fat in a serving disqualified the company from making its current cholesterol-free claims.

The letter, originally reported by Bloomberg, was written on August 12; it gave the company 15 working days to respond to the letter.