The victimization of civilians and combatants during internal conflicts causes large long-term socioeconomic costs. Unfortunately, it is not clear whether peace negotiations can significantly reduce this burden, as the risk of victimization may linger well after conflicts end. One key reason for the such persistence is the presence of antipersonnel landmines, which are hidden underground and remain active for decades. Looking at the recent experience of Colombia, 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.