A locking device (100) used for securing a heat sink (10) to a heat-generating component in accordance with an embodiment includes a pair of retainers (20). The locking device cooperates with a retention frame (30) to secure the heat sink to the heat-generating component. Each retainer (20) includes a handle (22) and a locking leg (24). The handle is pivotably mounted to fins of the heat sink via a pivot (225). The locking leg is made from a unitary sheet member and is connected to the handle at a location spaced apart from the pivot via which the handle is mounted to the heat sink. When the handle is brought to pivot about the pivot, the locking leg is driven to move in a direction to engage with the retention frame whereby the heat sink is firmly secured to the heat-generating component.