The reduction of ambiguous language is a commonly proposed strategy to remedy non-compliance with international obligations. The European Union conventional arms export control regime is a case in point; here, eliminating ambiguity has stood at the forefront among the strategies that have been proposed to remedy poor implementation. The point of departure of this article, however, is the observation that language-addressing strategies are largely inattentive to the underlying dynamics that caused ambiguity in the first place. Through tracing the formation and evolution of the regime, the article argues that the ambiguity of the export control regime is attributable to a configuration of underlying heterogeneity and resistance that is not conducive to a more precise language. Furthermore, the article argues that in order to explain the adoption, evolution and ambiguity of the regime, we need a theoretical model that moves away from the strong emphasis on norm dynamics prevalent in recent research on arms export control. While norm dynamics and a preference for export restraint have certainly influenced the adoption, evolution and design of the regime, the article highlights how the material interests of export promotion, security and sovereignty feature as more critical variables. This casts new light on the gap between export control commitments and export practice, and provides important clues about the prospects for efficient multilateral arms export control. Pushing the research agenda forward therefore hinges on bringing material interests back into the equation.