Employing the generalized likelihood ratio test and semidefinite programming (SDP), we derive two detectors, called the SDP and maximization in the reduced space (MRS) detectors for range-spread targets with unknown Doppler shift. It is confirmed that, when knowledge of Doppler frequency is unavailable or imperfect, the proposed detectors perform better than the conventional detector. The MRS detector also outperforms the SDP and conventional detectors in some cases, including when the range-spread target is highly fluctuating.