Mozilla chief executive Chris Beard is not happy with Windows 10.

In an open letter published addressed to Microsoft CEO Satya Nadella, he chided the Redmond, Washington-based company over the its apparent decision to take away “choice and control” from the user. Beard admits that his team tried to work it out with Microsoft, but it “didn’t result in any meaningful progress.”

To pressure Microsoft to “undo” its actions, Mozilla is encouraging users to tell the Windows 10 manufacturer to “hit Ctrl+Z” and bring back user choice.

At issue is Beard’s contention that when users upgrade to Windows 10 (which debuted yesterday), the new operating system wants them to have an Internet experience that Microsoft wants them to have — specifically with Microsoft’s new Edge browser. Although it’s “technically possible” to retain your previous settings and defaults, Beard believes that somehow Microsoft has buried these settings somewhere deep in the operating system that makes it hard to get to.

“With the launch of Windows 10 we are deeply disappointed to see Microsoft take such a dramatic step backward,” says Beard. In a separate post, he writes:

Sometimes we see great progress, where consumer products respect individuals and their choices. However, with the launch of Windows 10, we are deeply disappointed to see Microsoft take such a dramatic step backward. It is bewildering to see, after almost 15 years of progress bolstered by significant government intervention, that with Windows 10, user choice has now been all but removed.

Although Beard says that his team has reached out to Microsoft prior to publishing this letter, nothing has been disclosed about how far talks have gone and why no progress was made.

This isn’t the first time Microsoft has been ripped over user control. In 1998, the U.S. Department of Justice filed an antitrust suit against the technology company claiming that it was monopolizing the computer software industry in coupling Windows with Internet Explorer. It was alleged at the time that Microsoft had attempted to persuade Netscape to not compete against it. Netscape obviously didn’t comply.

Additionally, federal authorities claimed that Microsoft was misusing its stranglehold on the operating system world by requiring manufacturers to adopt certain standards that Microsoft set. To Beard, it doesn’t want Microsoft to “roll back the clock” to that era.

We’ve reached out to Mozilla for comment and will update this if we hear back.

Update: A Microsoft spokesperson has responded to VentureBeat’s inquiry, saying: “We designed Windows 10 to provide a simple upgrade experience for users and a cohesive experience following the upgrade. During the upgrade, consumers have the choice to set defaults, including for web browsing. Following the upgrade, they can easily choose the default browser of their choice. As with all aspects of the product, we have designed Windows 10 as a service; if we learn from user experience that there are ways to make improvements, we will do so.”

Here’s Beard’s open letter to Microsoft: