A mobile ad hoc network (MANET) facilitates mobile hosts to communicate with one another based on wireless infrastructure. There are no base stations in ad hoc networks and the mobile hosts act as routers for data packets. Since the mobile hosts in a MANET keep moving, topological changes take place frequently in the network. This cause routing information kept by the nodes to get outdated easily. Effective ways of getting updated routing information is needed. This problem becomes more complex in wireless networks, where bandwidth is limited. This paper proposes an improved dynamic source routing (DSR) algorithm as a solution to this problem. The proposed algorithm, the Improved Dynamic Source Routing (I-DSR), has a hybrid feature, combined proactive and reactive, that enables all the hosts to get updated changing topology information with a low cost in communication instead of enabling only a few hosts to get the information when there is a route request for a new moved destination. In anticipation of the need of a route request to the new moved destination by other hosts, the operations in the algorithm are designed to eliminate these needs for route request flooding and eventually generate a small number of control packets. Through simulations, we demonstrate that I-DSR gives better network performance than the well-known on-demanding routing protocol, Dynamic Source Routing (DSR) Protocol. As it is improved from DSR, it just needs a few modification on DSR and is easy to implement.