The invention relates to a waste heat recovery system (3) for an internal combustion engine (1), having a working fluid circuit (19) with a condenser (31) that is also connected to a working fluid cooling circuit (34), and wherein the working fluid cooling circuit (34) has a cooler (35). The invention provides a waste heat recovery system (3) having a working fluid cooling circuit (34) which is improved in comparison to one design of a working fluid cooling circuit (34). This is achieved by the working fluid cooling circuit (34) having a cooler bypass (46). This configuration makes it generally possible for part of the coolant volume flow to be routed past the cooler (35). This is advantageous in particular at low temperatures since otherwise very low pressures arise in the working fluid cooling circuit (34).