A clip (50) for securing a heat dissipating device to a heat source comprises a spring arm (510) and an ear (530). The spring arm comprises two wires (512) substantially parallel to each other, a hook (514) formed at one end of the spring arm to connect ends of the wires and two barbs (516) each formed at another end of each of the wires. A central portion of each of the wires projects downwardly. The ear comprises a main body (530a), two notches (532) in an upside of the main body and a clamping unit (537) at a downside of the main body. Each of the notches comprises from above to below an insertion slot (5321), an elongated sliding slot (5323) and a retaining slot (5325). The spring arm engages with the ear with the barbs extending into the insertion slots, and the wires are slideable downwardly along the sliding slots to be fixed in the retaining slots.