The present application relates to an operating unit for a breast pump system. The operating unit comprises a housing and a vacuum pump received in said housing. The housing has a connector (15) for attaching a tube and an outer surface (11) about which a tube can be wrapped. At least a section of the outer surface (11) is curved so that the tube can be wrapped about the housing without buckling. The outer surface (11) comprises a recess (14) and the connector (15) is located in the recess (14), wherein a surface of the recess (14) distends away from the connector (15) so that when a tube is attached to the connector (15), a portion of the tube proximal to the connector (15) does not buckle.