Agent for treating fibers containing keratin, particularly human hair, comprising, in a cosmetically acceptable carrier: (a) at least one amphiphilic, cationic polymer having at least one structural unit of formulae (I) to (IV), wherein; R1 and R4 are independently hydrogen or a methyl group, X1 and X2 are independently oxygen or an NH group, A1 and A2 are independently an ethane-1,2-diyl, propane-1,3-diyl or butane-1,4-diyl group, R2, R3, R5 and R6 are independently a (C1 to C4)-alkyl group, R7 is a C8 to C30)-alkyl group and; (b) at least one film-forming cationic and/or stabilizing cationic polymer. The invention also relates to use of agents for temporarily styling hair and for haircare, particularly as an aerosol hairspray or mousse.