Received signal strength (RSS)-based wireless localization is easy to implement at low cost. In practice, exact positions of anchors may not be available. This paper focuses on determining the location of the source in the presence of inaccurate position of anchors based on RSS directly. We at first use Taylor expansion and a min-max approach to get the approximate maximum likelihood estimator of the source coordinates. Then we propose a relaxed semi-definite programming model to circumvent the non-convexity. We also propose a rounding algorithm considering both the inaccurate source location and the inaccurate anchor location. Simulation results together with analysis are presented to validate the proposed method.