The action of X-rays is commonly invoked to explain the wind properties of low-luminosity O-type stars. These stars have significantly smaller mass loss rates than predicted radiation-driven wind theories. In this respect they may resemble the first generation of supermassive stars in the early universe which presumably had weak winds due to their low metallicity. We present the high-resolution X-ray spectrum of a weak-wind star, mu Col, and discuss the potential for X-ray emission line strengths and profiles to discriminate among proposed mechanisms for the generation of X-rays in stellar winds, and in resolving the weak-wind problem.