Dr. Anthony Fauci once again got into a bit of back and forth with a Fox News anchor on Tuesday, this time pushing back against Sandra Smith’s complaint that the “goalposts keep moving” on mask use.

During an appearance on Fox News’ America’s Newsroom on Monday, Fauci—who now serves as the chief medical adviser to President Joe Biden—shot down anchor Bill Hemmer’s attempt to make the interview about President Donald Trump, noting that Hemmer’s colleague Dana Perino had just said they should “put that behind us” and move forward.

Just a day later, Fauci once again showed up on Fox, this time sitting down for a comprehensive interview with Smith and co-anchor John Roberts. For the most part, the interview was fairly collegial, as the two anchors focused their questions on the Biden administration’s coronavirus policies and vaccine distribution plans.

Towards the end of the conversation, however, it got a bit testy when Smith hit on Fauci’s recent remarks that double-masking makes “common sense” and is very likely more effective in protecting against viral spread than wearing a single mask.

“So if you have a physical covering with one layer, you put another layer on, it just makes common sense that it likely would be more effective. That’s the reason why you see people either double masking or doing a version of an N95,” Fauci said last week.

“Dr. Fauci, seems like the goalposts keep moving,” Smith stated, noting that California is having additional problems as new coronavirus strains are popping up.

“All of us are trying to do what it takes to stay safe. We’re all wearing our masks and hope that most people are. Now we’re hearing we should wear two,” she continued before snarking: “If I go to the grocery store, do I wear two, do I wear three? Is it safer to wear eight? Where does it stop?!”

Fauci, meanwhile, retorted that the “discussion is changing, not the goalposts,” adding that the Centers for Disease Control and Prevention is not officially recommending anyone to wear double masks.

“What they’re saying is, ‘You know what would be a good start? If everybody wears at least one mask,’” he further explained. “I think that would be important. So the CDC recommendations have not changed. What we’re trying to do is to get individuals that are not wearing masks to wear masks.”