An electric machine is disclosed herein comprising a stator and a rotor opposing the stator. A plurality of slots are formed in the rotor, each of the plurality of slots including a stator side and an opposing side. Each of the plurality of slots further include a central magnet retaining portion positioned between two opposing end portions of the slot. The central magnet retaining portion is defined by at least one protrusion formed on the stator side of the slot. The at least one protrusion forms a neck in the slot and separates the magnet retaining portion from one of the end portions. A magnet is positioned in the magnet retaining portion of the slot. The two opposing end portions of the slot are empty, providing voids at the ends of the slot.