In this letter, we present a fixed-length robust joint source-channel coding (RJSCC) scheme for transmitting images over wireless channels. The system integrates a joint source-channel coding (JSCC) scheme with all-pass filtering source shaping to enable robust image transmission. In particular, we are able to incorporate both transition probability and bit error rate of a bursty channel model into an end-to-end rate-distortion (R-D) function to achieve an optimum tradeoff between source coding accuracy and channel error protection under a fixed transmission rate. Experimental results show that the proposed scheme can achieve not only high peak signal-to-noise ratio performance, but also excellent perceptual quality, especially when the channel mismatch occurs.