The present invention relates to a thermoplastic composition with improved hydrolytic stability, comprising: 30 to 50 percent by weight of a polybutylene terephthalate (PBT) having a carboxylic end group concentration (CEG) of 40 to 120 mmol/kg and an intrinsic viscosity of 0.63 to 0.68 dl/g as measured in a 60:40 phenol/tetrachloroethane; 0.01 to 0.1 percent by weight of a catalyst; 0.01 to 5 percent by weight of an epoxy chain extender; wherein all weight percents are based on the total weight of the composition.