Twitter has disclosed a bug that shared some iOS users’ data with an unnamed partner, even if the users did not opt to share data.

The micro-blogging platform said it discovered that “we were inadvertently collecting and sharing iOS location data with one of our trusted partners in certain circumstances”.

The bug affected Twitter’s iOS user base and they’ve since been notified of the issue.

“We have confirmed with our partner that the location data has not been retained and that it only existed in their systems for a short time, and was then deleted as part of their normal process,” Twitter said in a statement on Monday.

For people who used more than one account on Twitter for iOS and opted into using the precise location feature in one account, the location data was “accidentally collected” when they were using any other account(s) on that same device for which they had not turned on the precise location feature.

“Due to a bug in Twitter for iOS, we inadvertently collected and shared location data (at the zip code or city level),” the Twitter Support team said in a tweet.

“We have fixed this problem and are working hard to make sure it does not happen again. We have also communicated with the people whose accounts were impacted to let them know the bug has been fixed.”

It’s unclear at this time when this location sharing took place, or for how long.