Recent years have seen increasing interest in systems that reason about and manipulate executable code. Such systems can generally benefit from information about aliasing. Unfortunately, most existing alias analyses are formulated in terms of high-level language features, and are unable to cope with features, such as pointer arithmetic, that pervade executable programs. This paper describes a simple algorithm that can be used to obtain aliasing information for executable code. In order to be practical, the algorithm is careful to keep its memory requirements low, sacrificing precision where necessary to achieve this goal. Experimental results indicate that it is nevertheless able to provide a reasonable amount of information about memory references across a variety of benchmark programs.