Defendant who served time in presentence custody after October 1, 2011 for a crime committed before this date was not entitled to have his presentence conduct credits calculated under the October 1, 2011 version of Penal Code section 4019. Appellant was convicted of being a felon in possession of a firearm with a strike prior. The offense occurred on June 1, 2011. In July of 2012, appellant was sentenced to six years in state prison with credit for 415 actual days plus 415 conduct days. On appeal, the court questioned the award of day-for-day conduct credits. Appellant did not qualify for day-for-day conduct credits under the version of Penal Code section 2933 in effect at the time the crime was committed; his prior strike required calculation of conduct credits under section 4019. Effective October 1, 2011, section 4019 was amended to provide two days of conduct credit for every two days of time actually served. The amendment applies to prisoners who are in custody for a crime committed on or after October 1, 2011. The former version of section 4019 only allotted two days of conduct credit for every four days actually served. Relying on the rule of lenity, appellant argued that he was properly granted two days of conduct credit for each two days served in custody after September 30, 2011 pursuant to the amended version of section 4019. The court rejected appellant’s contention and reduced the prior award of presentence conduct credits, holding that the credits should be calculated under the version of section 4019 in effect at the time appellant committed his crime. The rule of lenity did not apply because the section 4019 amendment was expressly prospective and there was no ambiguity in the statute.