The trial court is not required to instruct, sua sponte, on the defense of mistake of fact if the jury is otherwise instructed on the required mental state of the offense. Appellant was charged with and convicted of petty theft for stealing a $20 hoodie from a Walmart store. The evidence presented at trial was that appellant put the hoodie over his shoulder. He then selected other items, paid for them, and left the store, with the hoodie still over his shoulder. On appeal, appellant claimed that the trial court erroneously failed to instruct the jury, sua sponte, on the defense of mistake of fact. He contended that because there was sufficient evidence that he did not intend to steal the hoodie and only forgot he had it when he walked out the store, the court was required to instruct on mistake of fact. Affirmed. First, the court observed that the mistake of fact defense is inapplicable in these circumstances. A defendant’s mistaken belief must relate to a set of circumstances which, if existent or true, would make the act charged an innocent act. The act of forgetting about the hoodie does not amount to a mistaken belief which would have made defendant’s act of walking out of the store without paying for it lawful. And, even if the evidence supported an instruction on mistake of fact, the trial court did not have a duty to instruct on the defense sua sponte. Defenses that serve only to negate the mental state element of the charged offense do not invoke a court’s sua sponte instructional duty when the jury is properly instructed on the mental state element, as it was here.