In a washer fluid pump (2) for a window cleaning system (3) of a motor vehicle, a ventilation duct (21) of an electric motor (9) is guided in a labyrinth from a first plane (22) arranged in the electric motor (9) into the environment via a second plane (24) arranged in a collecting space (23). For this purpose, the ventilation duct (21) has two first sections (20) which lead vertically from the electric motor (9) into the collecting space (23), and two second sections (26) which open out vertically from the collecting space (23) into the environment. The first and the second sections (20, 26) are offset with respect to one another by 90°, so as to prevent an infiltration of spray water into the electric motor (9).