A probation condition is subject to the "'void for vagueness'" doctrine. (People v. Lopez (1998) 66 Cal.App.4th 615, 630.) The "underlying concern" of the void for vagueness doctrine "is the core due process requirement of adequate notice. 'No one may be required at peril of life, liberty or property to speculate as to the meaning of penal statutes. All are entitled to be informed as to what the State commands or forbids.'" (People ex rel. Gallo v. Acuna (1997) 14 Cal.4th 1090, 1115.) The question here is whether the void for vagueness doctrine demands an explicit knowledge requirement in the challenged probation conditions. We conclude that it does. Given "the rule that probation conditions that implicate constitutional rights must be narrowly drawn, and the importance of constitutional rights," the knowledge requirement in probation conditions "should not be left to implication." (People v. Garcia (1993) 19 Cal.App.4th 97, 102.) In People v. Lopez, supra, 66 Cal.App.4th 615, the Court of Appeal concluded that a condition which prohibited the defendant from "associating with persons not known to him to be gang members" was overbroad and modified the condition to prohibit association with known gang members. (Id. at pp. 628-629.) For the same reason, the court modified a condition which would have prohibited the defendant from "displaying indicia not known to him to be gang related," so that it applied only to those indicia that the defendant knew to be gang related. (Id. at p. 629.) "A condition of probation which requires or forbids conduct which is not itself criminal is valid if that conduct is reasonably related to the crime of which the defendant was convicted or to future criminality." (People v. Lent (1975) 15 Cal.3d 481, 486; abrogated by Proposition 8 on another ground as recognized in People v. Wheeler (1992) 4 Cal.4th 284, 290-291.) Terms and conditions of probation are reviewed under the highly deferential abuse of discretion standard. (People v. Balestra (1999) 76 Cal.App.4th 57, 63.) A sentencing court violates this standard only when its probation condition determinations are arbitrary, capricious, or exceed "the bounds of reason, all of the circumstances being considered." (People v. Welch (1993) 5 Cal.4th 228, 234.)