The invention relates to 5- ( ( (1R, 1aS, 6bR) -1- (6- (trifluoromethyl) -1H-benzo [d] imidazol-2-yl) -1a,6b-dihydro-1H-cyclopropa [b] benzofuran-5-yl) oxy) -3, 4-dihydro-1, 8-naphthyridin-2 (1H) -one (Compound 1) maleate salts, in particular the sesqui-maleate salt and its crystalline forms, methods of preparation, pharmaceutical compositions, and therapeutic uses for treatment of diseases or disorders mediated by BRAF or other kinases.