Facebook is in trouble with media buyers after it was revealed the social platform had overestimated average viewing time for video ads over the past two years.

An article by The Wall Street Journal found that Facebook was only counting video views of more than three seconds when calculating its “Average Duration of Video Viewed” metric. By eliminating videos under three seconds, the average engagement was inflated.

The company said it was introducing a new metric, “Average Watch Time”, which will replace the earlier metric.

In a statement to B&T, a Facebook representative said:

“We recently discovered an error in the way we calculate one of our video metrics. This error has been fixed, it did not impact billing, and we have notified our partners both through our product dashboards and via sales and publisher outreach. We also renamed the metric to make it clearer what we measure. This metric is one of many our partners use to assess their video campaigns.”

The news was tweeted by Twitter Australia’s MD Karen Stocks, the shade of it all:

Facebook Overestimated Key Video Metric For Two Years https://t.co/oewp6nAhGQ via @WSJ

— Karen Stocks (@KazStocks) September 23, 2016