Thermoplastic molding compositions, comprisingA) from 10 to 98% by weight of at least one thermoplastic polyester,B) from 0.01 to 50% by weight ofB1) at least one highly branched or hyperbranched polycarbonate with an OH number of from 1 to 600 mg KOH/g of polycarbonate (to DIN 53240, Part 2), orB2) at least one highly branched or hyperbranched polyester of AxBy type, where x is at least 1.1 and y is at least 2.1, or a mixture of these,C) from 1 to 40% by weight of an impact-modifying polymer,D) from 0 to 60% by weight of other additives,where the total of the percentages by weight of components A) to D) is 100%.