A probation condition that prohibits an identified activity by probationer but fails to incorporate probationer’s knowledge of the specifics of the activity, is unconstitutionally vague. Appellant was convicted of exposing himself to a three-year-old girl. He had prior convictions for indecent exposure to children and receiving child pornography. The trial court granted him probation with conditions requiring him to have no contact with persons under the age of 18 and to possess no sexually stimulating material deemed inappropriate by the probation officer. Appellant’s failure to object to the conditions in the trial court did not result in forfeiture on appeal as the claims involved a pure question of law, easily remedied by modification. (In re Sheena K. (2007) 40 Cal.4th 875.) The appellate court found that because the conditions did not incorporate probationer’s knowledge that the persons were under 18 or that he be advised by the probation officer that the material was inappropriate, they were unconstitutional. However, the Court of Appeal has the power to modify the conditions of probation so as to render them constitutional and did so.