This paper studies TCP performance improvement in wireless and heterogeneous networks using Forward Error Correction (FEC) technique driven by TCP semantics. In the proposed scheme, called TCP-aware FEC, the amount of redundancy added to a packet at the sender node corresponds to the level of error protection and is computed as a function of TCP congestion window. The TCP-aware FEC becomes stronger for low congestion window values (experienced after a packet loss is detected), while the amount of added redundancy is reduced for the large window values approaching the capacity of the end-to-end link.