The Electronic Privacy Information Center, a Washington D.C. nonprofit that focuses on privacy issues, asked the FTC to “commence an enforcement action against Google with the aim of divesting the company of Nest and requiring also that Google disgorge the data it wrongfully obtained from Nest customers,” according to a copy of the letter posted on EPIC’s website.

The issue came to light when Google let Nest Secure users know earlier this month that its Google voice assistant, which requires a microphone to hear commands, was also coming to the device. There was just one problem: A microphone was never disclosed in the Nest Secure published specs. The existence of the microphone was never supposed to be a secret, according to Google.

“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,” a statement from Google said. It added that “the microphone has never been on and is only activated when users specifically enable the option.”

The company said the microphone was in the device so it could be enabled to support future features, such as detecting the sound of broken glass.

Ever since Nest came into the Google family, the partnering has been of concern to EPIC. In 2014, the privacy group filed a complaint with the FTC objecting to Google’s $3.2 billion acquisition of the smart home company and chided the FTC for failing to “address significant privacy concerns” by the acquisition.

In a decision unrelated to EPIC’s complaint, Google spun off Nest in 2015 when it created Alphabet as its holding company. However Nest rejoined Google last year as the search giant moved to align its artificial intelligence and hardware verticals closer together, allowing for more collaboration—especially as it positioned itself to compete with Amazon’s Alexa.

EPIC closed the letter by telling the FTC it “should have conducted a more rigorous review” of the acquisition in 2014.

The FTC did not immediately respond to a request for comment.