Tim Cook and Silicon Valley are once again speaking out against anti-LGBT laws.

The out Apple CEO and 13 other tech leaders, including Facebook’s Mark Zuckerberg and the head of Google, sent a letter on Saturday to Texas lawmakers warning them against passing a so-called bathroom bill, according to the Dallas News, which obtained a copy.

Although the legislative session in Texas ends today, Lt. Gov. Dan Patrick called on Friday for a special session devoted solely to passing his anti-transgender law. It would ban transgender people from using the bathroom that matches their gender identity, among other forms of discrimination in locker rooms and more. Now Gov. Greg Abbott must decide whether to call lawmakers into session.

The CEOs — including the leaders of Amazon, Celanese Corp., Cisco, Dell, Gearbox, GSD&M, Hewlett Packard, IBM, Microsoft, Salesforce, and Silicon Labs — advised against any move that limits rights for transgender people. They described themselves as “large employers in the state” that are “gravely concerned that any such legislation would deeply tarnish Texas' reputation as open and friendly to businesses and families.” They made the usual case that being anti-LGBT hurts a state’s economy. "Our ability to attract, recruit and retain top talent, encourage new business relocations, expansions and investment, and maintain our economic competitiveness would all be negatively affected,” the CEOs wrote.

Business leaders have many times come to the side of LGBT activists who are fighting a rash of anti-LGBT laws in a number of incarnations.

In Indiana, where Vice President Mike Pence infamously signed a “license to discriminate” in 2015 as governor, it was the CEOs of SalesForce and Yelp that made headlines. Earlier in 2014 it was Apple that was a leading voice in Arizona, where former governor Jan Brewer nixed a similar “license to discriminate.” Apple threatened to kill plans for a factory in the state.

Laws took a particularly anti-transgender bent in North Carolina, where former governor Pat McCrory signed a law preventing transgender people from using the bathroom that matches their gender identity whenever in a state building. He and state Republicans also banned any local government from including either sexual orientation or gender identity in their anti-discrimination laws — effectively making it OK to discriminate.

The Associated Press reports the state has since lost $3.76 billion in business. The greatest loss was a PayPal facility that isn’t being constructed. McCrory also lost reelection. Democratic governor Roy Cooper this year passed a delay of the law’s effects and proclaimed it undone, even though activists don’t agree about the effects of his fix.

The Texas Tribune reports that Abbott will decide this week whether to call a special session, which might not include a bathroom bill on the agenda. Abbott promised a special session would be “only on the topics that I choose at the time of my choosing.”