In a surprise move last week, Microsoft announced that it will allow iOS and Android users free access to its Office software.

Yes, that’s right. The entire Microsoft Office Suite is available to iOS and Android users. That means that people who don’t own a Windows device and are on an entirely different ecosystem than Windows, have access to Excel, Outlook, Word and PowerPoint apps.

The move is meant to attract iPhone, iPad, and Android users to its Office Suite, while ensuring that Microsoft stays relevant in the global mobile device market. Yet, what Microsoft might end up doing in the process is hurting its own brand of mobile devices, Microsoft Lumia (the newly branded Windows Phone) and Microsoft Surface.

Earlier this year, Microsoft released Office for iPad, which paved the way for this total Office takeover. But last week’s move is still a surprise because Microsoft is allowing iOS and Android users free access to stand-alone apps, something that Windows mobile device users don’t have.

All Windows users must be subscribed to Office 365 or have paid for the Office 2013 Suite, and Windows mobile device users are stuck with just Office Mobile.

Microsoft spends millions on advertising and marketing to promote its brand, beating other tech giants like Dell and Apple.

Lumia and Surface lag behind other devices in the market, prompting some analysts to suggest that Microsoft should just kill the brands altogether. Microsoft says, “No way,” because its spending a lot of money to get big companies to use its brand and its more focused on “mobility” rather than market share.

Now, Microsoft is touting its software on other companies’ devices.

By making these apps free for iOS and Android users, Microsoft is hindering the sales of its own devices and making other mobile devices seem more attractive. Of course, Microsoft can’t hold its Office Suite hostage on its own OS, but it can make these apps pay to use like they are for Windows users. Surely that can’t be entirely detrimental to its business model.

But if Microsoft really wants to promote its own devices, it should make sure that Office is available everywhere and for everyone, as its slogan suggests. Windows mobile device users should not get the raw end of the bargain.

John Case, Microsoft Office corporate vice president, said in a statement that he was excited about releasing the new apps to the world. He even hinted that more was to come in the first quarter of 2015.

Our vision of Office everywhere wouldn’t be complete without Windows, so I’m pleased to confirm that new, touch-optimized Office apps for Windows 10 are in the works and we’ll have more to share soon.

Microsoft plans to allow Windows users access to these same apps that iOS users have access to in early 2015 when it releases Office for Mac. Can I stop paying for my Office 365 subscription now?