Credit: Courtesy of TMZ

Reality check for Stephanie Pratt: the Hills star might go to jail.

Pratt, 23, was formally charged Wednesday with suspicion of driving under the influence, TMZ reports. Her potential sentence: up to six months in jail and a $1000 fine.

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Pratt was arrested (with $5000 bail) in the early hours of Oct. 18 after leaving castmate Holly Montag's birthday shindig at L.A. club Empire.

Two breathalyzer tests registered .08 and .09; the legal limit is .08.

Spencer's little sister has admitted in the past to drug and alcohol addiction -- as well as a battle with bulimia.

On Tuesday, the star wrote via Twitter "inner peace...keeping the faith-its good to be reminded that its all about perspective".