The victimization of civilians and combatants during internal conflicts causes large and persistent socioeconomic costs. Moreover, it is not clear whether peace negotiations can significantly reduce this burden, as some sources of harm persist well after conflicts end. This is the case of antipersonnel landmines, which are hidden underground and remain active for decades. Looking at the recent experience of Colombia, and using a difference-in-differences empirical strategy, we study the conditions under which peace agreements reduce landmine blasts and victimization. Our findings point to the importance of post-conflict information sharing and comprehensive humanitarian mine clearance campaigns.