Halide perovskite materials are touted as tolerant to the presence of native structural defects; native refers to "intrinsic" lattice point defects, including vacancies and interstitials, which may or may not be induced by an extrinsic impurity/defect. That is to say, with the possible exception of positively charged iodine interstitials , native defects are optoelectronically inert and do not prevent these materials from performing their primary photovoltaic or electroluminescent function. This limited tolerance to crystallographic imperfections may mean native defects in perovskites are superficially benign, but their interactions with extrinsic species are certainly consequential. Reactions between native halide vacancies and molecular oxygen influence doping and facilitate degradation. Moreover, it is understood that concentrations of native defects and extrinsic impurities are directly linked. Ionic conductivity measurements of undoped and doped PbBr2 crystals illustrate how, for example, Na + impurities occupying Pb 2+ sites induce halide vacancies for charge neutrality, which are available to participate in ionic conduction. We speculate that halide perovskite defect populations are similarly dominated by impurities present within the reagents, a result of using processing additives, and released by in situ reactions during synthesis. Further, a growing body of literature indicates that the full efficiency and stability potential of halide perovskite materials will, to some degree, be unlocked by improving precursor quality, motivating us to scrutinize the impurity content of PbI2 reagents for perovskite applications.