President Obama commuted a convicted drug trafficker’s prison sentence on Tuesday after it was discovered that the prisoner had been sentenced to three and a half extra years in prison due to a typo.

Ceasar Huerta Cantu, of Katy, Texas, pleaded guilty to marijuana trafficking and money laundering in 2006 as part of a plea bargain. Though Cantu should have only received 11 1/2 years, the judge sentenced him to 15 years as the result of a typo describing his crime as more severe than it actually was. The Associated Press reports that prosecutors accidentally entered Cantu’s “offense level” as 36 when it should have read 34.

Because Cantu’s legal team didn't notice the error before sentencing, they were unable to change the amount of time Cantu would serve. The Justice Department announced on Tuesday that Obama had signed an order to commute Cantu’s sentence down to its original length because of the typo.

"A judge ruled that Mr. Cantu did not discover this error in time to correct it through any judicial means; as a result, it can now only be rectified through clemency," a White House spokesperson told the Hill.

Cantu is incarcerated in a federal corrections institute in Oakdale, La. He's now set to be released in 2018.

Cantu is the 10th person to have their sentence commuted by Obama. In the president’s first term, he only commuted one sentence, but has since stepped up the use of his power. Obama in December commuted the sentences of eight prisoners convicted on crack cocaine charges, stating that the prisoners were convicted under outdated guidelines.

Obama has additionally pardoned 52 prisoners since taking office.