The negotiation process of a peace agreement is an uncertain period where adversaries can have a difficult time credibly guaranteeing their commitment to an approaching agreement. However, violence is often ceased before a peace agreement is signed, demonstrating their importance for understanding non-violent and violent behavior by warring actors. Furthermore, research finds that rebels at times comply with laws of war during conflict and negotiations. Hence, the purpose of this study is to derive a better understanding of rebel groups’ non-violent behavior, and whether it relates to the commitment problem and the negotiation process. This paper argues that by complying with international law, rebels can convey a signal with a peace-making objective, increasing the likelihood of a successful negotiation. Through a qualitative, structured and focused comparative case analysis of the FMLN in El Salvador and the NPFL in Liberia, the study finds that rebel’s compliance with IHL may serve as a costly signal that mitigates the credible commitment problem and leads to the signing of a successful peace agreement. However, further research is needed to support this hypothesis.