Microsoft is joining the tech cry for Britain to stay in the EU

The so-called Brexit (Britain exit) referendum will ask U.K. voters on June 23 whether the country should leave the 28-state EU. Proponents say membership in the union has hurt Britain’s economy and opens the country up to too much immigration.

Boris Johnson, London’s colorful former mayor, has compared the EU to Hitler. Polls suggest the vote may be tight.

IBM, Cisco Systems, and Hewlett Packard Enterprise also oppose Brexit. As multinational companies, they often rely on flows of capital and employees across borders.

Microsoft said membership in the EU makes Britain a more attractive place to do business. The Redmond, Washington, company opened its first international office in the U.K. in 1982 and has 5,000 employees in the country, Microsoft’s U.K. CEO Michel Van der Bel wrote in a blog entry posted Tuesday.

“Our commitment to our staff and business here remain firm, but we also believe the U.K. remaining in the EU supports important criteria for continued and future investment by Microsoft and others,” Van der Bel said.

For example, researchers at the company’s R&D lab in Cambridge want and need to work alongside others from across the region, he said.

In addition to its own employees, Microsoft’s business in the U.K. has created a network of about 25,000 British partner companies, the company says.

Many multinational businesses are against the Brexit proposal. In February, executives from IBM, Cisco Systems, BT Group, Vodafone, and General Electric signed an open letter to the Times of London opposing the plan. HPE has also come out against Brexit, according to a Bloomberg report.