The Leonine Prayers are a set of prayers that from 1884 to early 1965 were prescribed by the Popes for recitation after Low Mass. They are still sometimes used at celebrations of the Tridentine Mass today. The final form of the Leonine Prayers consisted of three Ave Marias, a Salve Regina followed by a versicle and response, a prayer for the conversion of sinners and the liberty and exaltation of the Catholic Church, and a prayer to Saint Michael the Archangel. Pope Pius X permitted the addition of the invocation "Most Sacred Heart of Jesus, have mercy on us", repeated three times.