Microsoft’s AR goggle test program with the US Army has hit some bumps, with soldiers reporting headaches and nausea.

Microsoft scored a $21.9 billion contract to provide the US Army with augmented reality (AR) goggles. The contract is one of the biggest for augmented reality integration in a real-world application.

Unfortunately for Microsoft, the tests are not going well, according to The Seattle Times, with more than 80% of soldiers experiencing “mission-affecting physical impairments” after less than three hours of usage.

Nickolas Guertin, director of Operation Test and Evaluation, also noted that the Microsoft HoloLens is still failing too much with essential functions.

Despite the concerns, Guertin does not believe the project is a failure. Instead, he believes the Army should “prioritize improvements” before deploying HoloLens to more soldiers in an effort to minimize the “physical discomfort of users.”

Ultimately, the issues the US Army is facing are not uncommon with virtual reality (VR) and AR, with many users experiencing dizziness, headaches, and nausea when using VR equipment for any length of time. While that may not be a deal-breaker for a home user, someone who can simply take off the headset and take a break, it’s a major problem for soldiers that will be relying on the headsets for critical information.