Embodiments may involve the adjustment of the way in which coverage areas are included in the active set of a wireless communication device (WCD), based on the codec that is currently associated with the WCD. An illustrative method involves a radio access network (RAN): (a) determining a codec that is associated with a WCD; (b) using the associated codec as a basis for determining a value for at least one active-set parameter for the WCD; and (c) sending a message to the WCD, wherein the message indicates the determined value for the at least one active-set parameter.