Quantized feedback about the channel state information (CSI) at the transmitter improves the error performance of MIMO systems. In literature, most of the work is done to improve the error performance of the orthogonal space time block codes (OSTBCs) using feedback of CSI from the receiver to the transmitter. In this letter, we study the performance of nonorthogonal space-time block codes (NOSTBCs) in a 2×1 multipleinput single-output system with diagonal weighting scheme; this scheme utilizes quantized one bit feedback with no delay from the receiver in a quasi-static Rayleigh fading channel. The considered NOSTBCs are Golden code and Silver code. Error-tolerant diagonal weighting parameter which improves the pair wise error probability (PEP) of the receiver is derived. The PEP performance of the considered set-up is studied for the complex-valued constellation like quadrature amplitude modulation. Simulation results indicate that similar to OSTBCs, the error performance of the NOSTBCs also improves with the proposed diagonal precoding scheme.