LINCOLN, Neb. (AP) — Some Nebraska prisoners serving time for driving under the influence were kept behind bars longer than they should have been because of sentencing miscalculations.

State officials discovered the snafu while correcting the sentences of inmates who had been scheduled for release too early.

A prisons spokeswoman wouldn’t answer specifics about the erroneous calculations, which were noted by the Nebraska Attorney General’s office.

Emails obtained through the newspaper’s public records request suggest that dozens of people convicted of DUI offenses may have served more time than needed before they were paroled.

The incorrect DUI sentences were based on an interpretation by the Department of Correctional Services’ legal staff. The attorney general’s office notified department officials in June that the interpretation was wrong.