Image placement accuracy is widely regarded as one of the factors limiting the application of x-ray lithography to very large scale integration. Image placement errors may arise during mask fabrication, during exposure, or with time and use. Consequently, substantial effort has gone into reducing patterning errors, controlling stress,and selecting optimal mask materials. Alternatively, heat loads may be intentionally applied to compensate known horizontal and vertical distortions in the x-ray mask. In this procedure, a send-ahead wafer is used to determine overlay throughout the exposure field, and the heat loading is tailored during subsequent exposures to correct any errors. The process is simplified for storage ring exposures because proper overlay needs to be maintained, at any given moment of time, only along the line being exposed by the x-ray beam. A wide range of corrections may be made, either to reduce mask distortions or to match distortions already present on the wafer. Experiments were performed projecting 0.31 W of heat in the form of light onto x-ray masks. Displacements of +/-5 nm/W/mu m of air gap were observed on an old AT&T boron nitride membrane mask, +/-7 nm/W/mu m of air gap on an IBM silicon membrane mask, and +/-11 nm/W/mu m of air gap on an IBM silicon carbide mask. This sensitivity should prove useful for correcting distortion with the 10 mu m gaps expected in the near future.