diff --git a/Source/missiles.cpp b/Source/missiles.cpp
index 2e39f5697..1872272b9 100644
--- a/Source/missiles.cpp
+++ b/Source/missiles.cpp
@@ -872,7 +872,7 @@ bool MonsterTrapHit(int m, int mindam, int maxdam, int dist, missile_id t, bool
 		monster._mhitpoints = 0;
 #endif
 	if (monster._mhitpoints >> 6 <= 0) {
-		StartMonsterDeath(m, -1, true);
+		StartMonsterDeath(monster, -1, true);
 	} else if (resist) {
 		PlayEffect(monster, 1);
 	} else {
diff --git a/Source/monster.cpp b/Source/monster.cpp
index dc70d8271..5b17fb5a5 100644
--- a/Source/monster.cpp
+++ b/Source/monster.cpp
@@ -1080,11 +1080,8 @@ void MonsterHitMonster(int monsterId, int i, int dam)
 	HitMonster(monsterId, dam);
 }
 
-void MonsterDeath(int monsterId, int pnum, Direction md, bool sendmsg)
+void MonsterDeath(Monster &monster, int pnum, Direction md, bool sendmsg)
 {
-	assert(monsterId >= 0 && monsterId < MaxMonsters);
-	auto &monster = Monsters[monsterId];
-
 	if (pnum < MAX_PLRS) {
 		if (pnum >= 0)
 			monster.mWhoHit |= 1 << pnum;
@@ -1115,11 +1112,11 @@ void MonsterDeath(int monsterId, int pnum, Direction md, bool sendmsg)
 	monster.position.tile = monster.position.old;
 	monster.position.future = monster.position.old;
 	M_ClearSquares(monster);
-	dMonster[monster.position.tile.x][monster.position.tile.y] = monsterId + 1;
+	dMonster[monster.position.tile.x][monster.position.tile.y] = monster.getId() + 1;
 	CheckQuestKill(monster, sendmsg);
 	M_FallenFear(monster.position.tile);
 	if (IsAnyOf(monster.type().type, MT_NACID, MT_RACID, MT_BACID, MT_XACID, MT_SPIDLORD))
-		AddMissile(monster.position.tile, { 0, 0 }, Direction::South, MIS_ACIDPUD, TARGET_PLAYERS, monsterId, monster._mint + 1, 0);
+		AddMissile(monster.position.tile, { 0, 0 }, Direction::South, MIS_ACIDPUD, TARGET_PLAYERS, monster.getId(), monster._mint + 1, 0);
 }
 
 void StartDeathFromMonster(int i, int mid)
@@ -1133,7 +1130,7 @@ void StartDeathFromMonster(int i, int mid)
 	NetSendCmdLocParam1(false, CMD_MONSTDEATH, monster.position.tile, mid);
 
 	Direction md = GetDirection(monster.position.tile, killer.position.tile);
-	MonsterDeath(mid, i, md, true);
+	MonsterDeath(monster, i, md, true);
 	if (gbIsHellfire)
 		M_StartStand(killer, killer._mdir);
 }
@@ -3193,7 +3190,7 @@ void LachdananAi(int monsterId)
 			if (!effect_is_playing(USFX_LACH3) && monster._mgoal == MGOAL_TALKING) {
 				monster.mtalkmsg = TEXT_NONE;
 				Quests[Q_VEIL]._qactive = QUEST_DONE;
-				StartMonsterDeath(monsterId, -1, true);
+				StartMonsterDeath(monster, -1, true);
 			}
 		}
 	}
@@ -3936,13 +3933,10 @@ void M_StartHit(int monsterId, int pnum, int dam)
 	M_StartHit(monsterId, dam);
 }
 
-void StartMonsterDeath(int monsterId, int pnum, bool sendmsg)
+void StartMonsterDeath(Monster &monster, int pnum, bool sendmsg)
 {
-	assert(monsterId >= 0 && monsterId < MaxMonsters);
-	Monster &monster = Monsters[monsterId];
-
 	Direction md = pnum >= 0 ? GetDirection(monster.position.tile, Players[pnum].position.tile) : monster._mdir;
-	MonsterDeath(monsterId, pnum, md, sendmsg);
+	MonsterDeath(monster, pnum, md, sendmsg);
 }
 
 void M_StartKill(int monsterId, int pnum)
@@ -3959,7 +3953,7 @@ void M_StartKill(int monsterId, int pnum)
 		}
 	}
 
-	StartMonsterDeath(monsterId, pnum, true);
+	StartMonsterDeath(monster, pnum, true);
 }
 
 void M_SyncStartKill(int monsterId, Point position, int pnum)
@@ -3977,7 +3971,7 @@ void M_SyncStartKill(int monsterId, Point position, int pnum)
 		monster.position.old = position;
 	}
 
-	StartMonsterDeath(monsterId, pnum, false);
+	StartMonsterDeath(monster, pnum, false);
 }
 
 void M_UpdateLeader(int monsterId)
diff --git a/Source/monster.h b/Source/monster.h
index fff2f4041..de7b9d0b7 100644
--- a/Source/monster.h
+++ b/Source/monster.h
@@ -309,7 +309,7 @@ void M_ClearSquares(const Monster &monster);
 void M_GetKnockback(Monster &monster);
 void M_StartHit(int monsterId, int dam);
 void M_StartHit(int monsterId, int pnum, int dam);
-void StartMonsterDeath(int monsterId, int pnum, bool sendmsg);
+void StartMonsterDeath(Monster &monster, int pnum, bool sendmsg);
 void M_StartKill(int monsterId, int pnum);
 void M_SyncStartKill(int monsterId, Point position, int pnum);
 void M_UpdateLeader(int monsterId);