In carrier-sense-multiple-access/collision-avoidance networks in which stations have different data rates, some stations are penalized because slow stations receive more time to transmit. Thus, a single low data-rate station unfairly brings down the throughput of the high data-rate stations. We introduce a simple and standard-compliant algorithm to fairly utilize the channel. We first provide a formulation for the throughput with mixed data-rate connections. To alleviate the low performance of the high data-rate stations, we introduce a mechanism that implements an adaptive scheme to adjust the packet size according to the data rate. With this scheme, stations occupy the channel for equal amounts of time. We then extend the scheme to a frame-aggregation scheme to show how different packet sizes affect performance.