A hot potato: While users might have welcomed Google’s announcement that its Nest Secure system was receiving Google Assistant functionality, the news came as a surprise—mainly because they had no idea the included Nest Guard device contained a microphone. Now, the tech giant has admitted it made an error in not revealing the feature.

Before announcing the arrival of built-in Google Assistant support, the Nest Guard’s product page made no mention of a microphone. The company has assured people that “the microphone has never been on, and is only activated when users specifically enable the option.” A recently updated version of the website now shows a mic is part of the system.

Speaking to Business Insider, Google admitted it had made an “error.”

“Security systems often use microphones to provide features that rely on sound sensing. We included the mic on the device so that we can potentially offer additional features to our users in the future, such as the ability to detect broken glass,” it said.

“The on-device microphone was never intended to be a secret and should have been listed in the tech specs. That was an error on our part.”

One of the components of the Nest Secure home security system, the Nest Guard is the brains of the setup, combining a siren, keypad, and motion sensor. With the addition of Google Assistant, owners can arm the system using their voice.

While Google may have genuinely made an error in not disclosing the microphone’s existence, some customers are unhappy about the situation, especially at a time when user privacy has become the tech industry’s most contentious topic.