diff --git a/code/game/machinery/doors/firedoor.dm b/code/game/machinery/doors/firedoor.dm
index 2a0dbd316a..e4284d459f 100644
--- a/code/game/machinery/doors/firedoor.dm
+++ b/code/game/machinery/doors/firedoor.dm
@@ -61,13 +61,17 @@
 		for(var/t in T.atmos_adjacent_turfs)
 			if(get_dir(loc, t) == dir)
 				var/turf/open/T2 = t
-				T.atmos_adjacent_turfs[T2] |= ATMOS_ADJACENT_FIRELOCK
-				T2.atmos_adjacent_turfs[T] |= ATMOS_ADJACENT_FIRELOCK
+				if(T2 in T.atmos_adjacent_turfs)
+					T.atmos_adjacent_turfs[T2] |= ATMOS_ADJACENT_FIRELOCK
+				if(T in T2.atmos_adjacent_turfs)
+					T2.atmos_adjacent_turfs[T] |= ATMOS_ADJACENT_FIRELOCK
 	else
 		for(var/t in T.atmos_adjacent_turfs)
 			var/turf/open/T2 = t
-			T.atmos_adjacent_turfs[T2] |= ATMOS_ADJACENT_FIRELOCK
-			T2.atmos_adjacent_turfs[T] |= ATMOS_ADJACENT_FIRELOCK
+			if(T2 in T.atmos_adjacent_turfs)
+				T.atmos_adjacent_turfs[T2] |= ATMOS_ADJACENT_FIRELOCK
+			if(T in T2.atmos_adjacent_turfs)
+				T2.atmos_adjacent_turfs[T] |= ATMOS_ADJACENT_FIRELOCK
 
 /obj/machinery/door/firedoor/closed
 	icon_state = "door_closed"
diff --git a/code/modules/atmospherics/environmental/LINDA_system.dm b/code/modules/atmospherics/environmental/LINDA_system.dm
index 033ea6d871..83eb5d8ef3 100644
--- a/code/modules/atmospherics/environmental/LINDA_system.dm
+++ b/code/modules/atmospherics/environmental/LINDA_system.dm
@@ -51,8 +51,6 @@
 			LAZYINITLIST(T.atmos_adjacent_turfs)
 			atmos_adjacent_turfs[T] = ATMOS_ADJACENT_ANY
 			T.atmos_adjacent_turfs[src] = ATMOS_ADJACENT_ANY
-			for(var/obj/machinery/door/firedoor/FD in T)
-				FD.UpdateAdjacencyFlags()
 		else
 			if (atmos_adjacent_turfs)
 				atmos_adjacent_turfs -= T
@@ -63,6 +61,10 @@
 		T.__update_auxtools_turf_adjacency_info(isspaceturf(T.get_z_base_turf()), -1)
 	UNSETEMPTY(atmos_adjacent_turfs)
 	src.atmos_adjacent_turfs = atmos_adjacent_turfs
+	for(var/t in atmos_adjacent_turfs)
+		var/turf/open/T = t
+		for(var/obj/machinery/door/firedoor/FD in T)
+			FD.UpdateAdjacencyFlags()
 	for(var/obj/machinery/door/firedoor/FD in src)
 		FD.UpdateAdjacencyFlags()
 	__update_auxtools_turf_adjacency_info(isspaceturf(get_z_base_turf()))