In this paper, we try to reduce the amount of control traffic of the optimized link state routing protocol (OLSR). OLSR is a proactive routing protocol for mobile ad-hoc networks (MANETs). OLSR is known well as a low control traffic routing protocol, since it adopts multipoint relays (MPRs). MPRs concept significantly reduces the number of broadcast messages during the flooding process. Although MPR concept is optimal for each node to transmit its messages to all two hop neighbors, we show there are still redundant control messages which can be piggybacked with other control messages in dense networks. This redundancy is caused by the selection procedure of MPRs, which run on each node independently of its neighbor nodes. In this paper, we propose a cooperative MPR selection procedure, to increase messages which are piggybacked into a single control packet. Through simulation, we demonstrate that the proposed cooperative MPR selection procedure reduces the number of routing packets in high-density network, and network reachability is kept similar to that of the conventional MPR selection procedure.