The invention concerns a skin-mountable medical device comprising a patch portion with a contact surface facing the skin of a patient during use, a process unit attached to the patch portion, and a plaster kit for securing the patch portion to the skin, wherein the plaster kit has a primary pad adapted to releasably adhere to at least a section of a peripheral skin surface surrounding the contact surface. According to the invention, the plaster kit further comprises at least one auxiliary pad which is connectable or connected to the patch portion and adapted to functionally replace the primary pad after a wearing time.
