Members of the HarperCollins union went on strike Thursday, after contract negotiations between the Big Five publisher and its 250 unionized employees once again failed, the New York Times reports.

The striking workers have been without a contract since April. In a news release issued last month, the union said it was seeking “higher pay, a greater commitment to diversifying staff, and stronger union protection.”

Olga Brudastova, the president of the union chapter, told Publishers Weekly that HarperCollins was no longer interested in scheduling negotiation sessions with the workers.

“We now get information that management is instructing non-union employees to avoid any mention of the strike and is planning to override our members’ out-of-office messages that mention it,” Brudastova said.

HarperCollins is dealing with falling profits and sales, Publishers Weekly reports, which it attributes partially to “Amazon’s reset of its inventory levels and rightsizing of its warehouse footprint.”

The publisher boasts an enormous roster of well-known authors that includes Ann Patchett, Karin Slaughter, Don Winslow, and Angie Thomas. Some writers published by HarperCollins expressed solidarity with the striking workers, including Elise Bryant, Katie Slivensky, and Maris Kreizman.

Laura Harshberger, a HarperCollins production editor, told the Times that the strike is “bigger than our paychecks.”

“This fight has really been focused on trying to make publishing a more diverse and equitable place that reflects our values and the books that we make,” Harshberger said.

Union members spread news of the strike on Twitter. Rachel Kambury, an editor at the press, wrote that the strike would last “for days, possibly weeks.”

“Let me reassure you that a strike isn’t something any of us union members are choosing to do lightly,” Kambury tweeted. “This is our backed-into-a-corner, last-ditch-attempt to end a management-imposed stalemate and reach a deal that is meaningfully beneficial to the lowest paid and most overworked employees, most of whom are women, many of whom are women of color, LGBTQIA+, disabled, or otherwise underrepresented in (and disproportionately impacted by) this industry.”

Michael Schaub, a journalist and regular contributor to NPR, lives near Austin, Texas.