Hillbilly Elegy author J.D. Vance is being criticized for a tweet in which he self-identified as a “nationalist,” Salon reports.

“As a parent of young children and a nationalist who worries about America’s low fertility I can say with confidence that daylight savings time reduces fertility by at least 10 percent,” the author tweeted on Sunday.

Some critics of Vance saw the use of the term “nationalism” as a reference to White nationalism, a racist movement that believe in racial segregation and the supremacy of White people.

“Thanks for letting us know about your fertility issues and your racism/xenophobia,” tweeted author Roxane Gay. “A twofer.”

Angela Rasmussen, a virologist at Columbia University, tweeted, “Huh? Of all the things to worry about right now, the US fertility rate ain’t one of them. Hillbilly Elegy dude’s Twitter reads like Children of Men fanfic.”

One Twitter user struck a similar note, writing, “America’s ‘fertility rate’ is an extremely normal thing to worry about, my dude!”

That tweet seemed to get under Vance’s skin. “[Y]ou might consider some student loans to buy a sense of humor,” Vance responded.

Salon said that Vance did not respond to a request for comment about his tweet.

Michael Schaub is a Texas-based journalist and regular contributor to NPR.