Former Rep. Anthony Weiner (D-N.Y.) reported to prison Monday morning to begin serving a 21-month sentence for sending sexually explicit text messages to a 15-year-old girl.

Weiner will serve his sentence at Federal Medical Center, Devens, a federal prison in Massachusetts.

The ex-lawmaker pleaded guilty in May to sending a North Carolina high school student explicit messages in early 2016, acknowledging he was aware of the girls age when he messaged her.