diff --git a/code/datums/ai/basic_mobs/basic_ai_behaviors/targeting.dm b/code/datums/ai/basic_mobs/basic_ai_behaviors/targeting.dm
index e5de231aff5..9305c398611 100644
--- a/code/datums/ai/basic_mobs/basic_ai_behaviors/targeting.dm
+++ b/code/datums/ai/basic_mobs/basic_ai_behaviors/targeting.dm
@@ -1,5 +1,5 @@
 /// List of objects that AIs will treat as targets
-GLOBAL_LIST_EMPTY_TYPED(hostile_machines, /atom)
+GLOBAL_ALIST_EMPTY(hostile_machines_by_z)
 /// Static typecache list of things we are interested in
 /// Consider this a union of the for loop and the hearers call from below
 /// Must be kept up to date with the contents of hostile_machines
@@ -39,9 +39,11 @@ GLOBAL_LIST_INIT(target_interested_atoms, typecacheof(list(/mob, /obj/machinery/
 
 	var/list/potential_targets = hearers(aggro_range, get_turf(controller.pawn)) - living_mob //Remove self, so we don't suicide
 
-	for (var/atom/hostile_machine as anything in GLOB.hostile_machines)
-		if (can_see(living_mob, hostile_machine, aggro_range))
-			potential_targets += hostile_machine
+	var/turf/mob_turf = get_turf(living_mob)
+	if(mob_turf?.z)
+		for (var/atom/hostile_machine as anything in GLOB.hostile_machines_by_z[mob_turf.z])
+			if (can_see(living_mob, hostile_machine, aggro_range))
+				potential_targets += hostile_machine
 
 	if(!potential_targets.len)
 		failed_to_find_anyone(controller, target_key, targeting_strategy_key, hiding_location_key)
diff --git a/code/datums/elements/hostile_machine.dm b/code/datums/elements/hostile_machine.dm
index cb846d830e8..0b67775ecfe 100644
--- a/code/datums/elements/hostile_machine.dm
+++ b/code/datums/elements/hostile_machine.dm
@@ -12,8 +12,41 @@
 	if(!GLOB.target_interested_atoms[target.type])
 		stack_trace("Tried to make a hostile machine without updating ai targeting to include it, they must be synced")
 #endif
-	GLOB.hostile_machines += target
+
+	if(ismovable(target))
+		RegisterSignal(target, COMSIG_MOVABLE_Z_CHANGED, PROC_REF(on_z_change))
+
+	add_to_z(target)
 
 /datum/element/hostile_machine/Detach(datum/source)
-	GLOB.hostile_machines -= source
+	UnregisterSignal(source, COMSIG_MOVABLE_Z_CHANGED)
+	remove_from_z(source)
 	return ..()
+
+/datum/element/hostile_machine/proc/on_z_change(atom/movable/source, turf/old_turf, turf/new_turf, same_z_layer)
+	SIGNAL_HANDLER
+
+	if(same_z_layer)
+		return
+	remove_from_z(source, old_turf.z)
+	add_to_z(source, new_turf.z)
+
+/datum/element/hostile_machine/proc/add_to_z(atom/target, z)
+	if(isnull(z))
+		var/turf/target_turf = get_turf(target)
+		z = target_turf?.z
+	if(!z)
+		return
+	if(!GLOB.hostile_machines_by_z[z])
+		GLOB.hostile_machines_by_z[z] = list()
+	GLOB.hostile_machines_by_z[z] |= target
+
+/datum/element/hostile_machine/proc/remove_from_z(atom/target, z)
+	if(isnull(z))
+		var/turf/target_turf = get_turf(target)
+		z = target_turf?.z
+	if(!z)
+		return
+	GLOB.hostile_machines_by_z[z] -= target
+	if(!length(GLOB.hostile_machines_by_z[z]))
+		GLOB.hostile_machines_by_z -= z