The disclosure provides a new, stable, pharmaceutically acceptable bis-tosylate salt form of 1-(4-fluoro-phenyl)-4-((6bR, 10aS)-3-methyl-2,3,6b,9, 10, 10a-hexahydro-1H,7H-pyrido[3′,4′:4,5]pyrrolo[1,2,3-de]quinoxalin-8-yl)-butan-1-one, together with methods of making and using them, and pharmaceutical compositions comprising them.