A bug in Twitter’s Android app has inflated video advertising metrics by up to 35 per cent, according to a person familiar with the matter.

Business Insider reports that Twitter has issued refunds to advertisers for over-billing video campaigns that ran between 7 November and 12 December 2016, after letting advertisers know about the error earlier this week.

“We recently discovered a technical error due to a Twitter product update to Android clients that affected some video ad campaigns from 7 November to 12 December,” a Twitter spokesperson told Business Insider. “Once we discovered the issue, we resolved it and communicated the impact to affected partners. Given this was a technical error, not a policy or definition issue, we are confident it has been resolved.”

The misreporting of ad metrics is not unique to Twitter in the world of social networking. Recently, Facebook also had its issues with inflated video advertising metrics. In September, it was revealed that Facebook overestimated video view time by up to 80 per cent. Earlier this month, the social network’s troubles would continue as it faced even more measurement problems. The Media Ratings Council is reported to be in talks with Facebook about auditing its metrics following its measurement struggles, Advertising Age reports.