diff --git a/server/gameserver/human.cc b/server/gameserver/human.cc
index 743c709..1943475 100644
--- a/server/gameserver/human.cc
+++ b/server/gameserver/human.cc
@@ -628,6 +628,7 @@ void Human::SyncAroundPlayers()
     for (auto& cell : grid_list) {
         for (Human* hum : cell->human_list) {
             hum->AddToNewObjects(this);
+            assert(hum->part_objects.find(this) != hum->part_objects.end());
         }
     }
 }