Over the past few decades, the definition of rape has been the focus of widespread attention in international law. However, the circumstance of age-related incapacity in its definition has been left unexplored. Whilst no definition of an age of sexual consent is found in international criminal law, though suggestions have been made in jurisprudence, other international legal frameworks have included clear and well-defined thresholds in their definitions, i.e. recruitment, trafficking, sale, prostitution, and pornography. This article argues that the vagueness of an undefined threshold in the rape definition, and the existing inconsistencies when compared to the other frameworks, are at odds with the evolving trends in international law on the treatment of consent and child victims. This leaves child rape victims at a comparative disadvantage, especially adolescent girls, who pervasively experience the consequences and harms derived from this vagueness and inconsistency.