Those hoping for a pair of Surface Earbuds this Christmas will be sorely disappointed. On the day of their planned release, Microsoft’s Panos Panay revealed a delay until spring 2020.

“Product-making is about the relentless pursuit to get all the details right, which takes time…sometimes more than we planned on,” he wrote on Twitter. “To ensure we deliver the best possible experience for you, our fans & customers, Surface Earbuds will now launch worldwide in Spring 2020.”

Panay did not reveal exactly why the Earbuds have been delayed. Early impressions noted the extreme comfort of the devices and noted no major issues. Endgadget did say the live caption feature had a second or two delay, but Microsoft chalked that down to poor WiFi at its Surface hardware event. The design is also controversial, but we don’t expect that to change drastically at this point.

Generally, truly wireless earbuds can be hard to get right. You have to not only ensure a stable Bluetooth connection but do so for both ears. There are many places Microsoft could have found issues with further testing, and with stiff Airpods competition, it needs to get it right.

As well as the usual audio chops, the Surface Earbuds have a touchpad on their large circular ends. They also house a dual microphone array, last up to 8 hours, and integrate with enterprise software.

Microsoft’s previous entry, the Surface Headphones, proved popular with consumers. Though expensive, they were praised for their comfortable fit and innovative adjustable noise cancellation. The Earbuds, meanwhile, don’t seem to support active noise cancellation at all.