The principle of prohibiting forced labour exists in both treaty and customary international law. However, there are limits to this prohibition, in that certain types of forced labour are actually permitted; this is the case for forced labour performed by prisoners of war (PoWs). This paper examines the legal regime applicable to such labour. It starts by setting out the current rules, following a brief historical review. It then explains the shortcomings of those rules, which are open to abuse and are not focused exclusively on the rights and interests of the PoWs, before proposing two possible ways of improving the situation by means of a systemic approach. The first is based on international humanitarian law itself, while the second is based on the complementary relationship between that body of law and international human rights law. Such improvements would give PoWs the right to perform any available work while continuing to require them to carry out work exclusively dedicated to running the PoW camp.