Last week, Cal Henderson, the co-founder and CTO at Slack, cast his vote in a U.S. election for the first time. Having immigrated to the U.S. on an L-1 visa, and then an H-1B visa, he was only recently granted full-blown citizenship in September.

Like many immigrant entrepreneurs in the U.S., Henderson feels deeply troubled over the prospect of a Trump Administration. "It's pretty terrible and terrifying," he said on the eve of Nov. 8th, while playing "Dungeons and Dragon" with fellow Slack employees and drinking booze. "It was a terrible time," he adds. "It's terrifying that this is actually happening in America."

President-elect Donald Trump has threatened to bar all Muslims from entering the country, and suggested building a "big, beautiful, powerful wall" across the southern border of the U.S. Recently, he said he would deport millions of undocumented immigrants at once. In the beginning of his campaign, Trump said that the 11 million immigrants in the country needed to go.

Henderson takes issue with Trump's stance on immigration from a personal standpoint -- As someone recently awarded American citizenship, and from a business perspective, as a co-founder.

Slack, which builds office communication software, employs a significant number of immigrants from around the world. "I don't have a constant fear of being deported now," said Henderson, "but I have a lot of friends that are also British expats who work in tech, and that's a terrifying situation for them."

Given that Trump has, more recently, reneged on some of his more controversial proposals, entrepreneurs point out that the future is uncertain. "It's unclear what a Trump presidency would do to affect that directly in the Slack case, but there's definitely a prevailing animosity towards all 'Other,' and that's something we're super against," Henderson said.

When it became clear last week that Trump had defeated Democratic candidate Hillary Clinton, the Slack co-founders posted in their company's "general announcements" channel, ensuring employees that the office culture would remain tolerant and diverse in the years to come.