A Portland band was set to do a concert at an Eastern Oregon prison.
But the show was canceled when a guard discovered pot in a guitar string bag.
The Alexa Wiley Band was scheduled to perform for inmates over the weekend.
Prison spokeswoman Vicki Reynolds says the marijuana was found during a mandatory inspection of the band's equipment.
A local paper reports state troopers confiscated the pot and detained the guitarist.
But he was later allowed to leave the prison.
