heretics LOVES this - Also ian's birthday!

code/modules/mapping/mapping_helpers/baseturf.dm

@@ -30,8 +30,8 @@
 	qdel(src)
 
 /obj/effect/baseturf_helper/proc/replace_baseturf(turf/thing)
-	var/list/baseturf_cache = thing.baseturfs
-	if(length(baseturf_cache))
+	if(length(thing.baseturfs))
+		var/list/baseturf_cache = thing.baseturfs.Copy()
 		for(var/i in baseturf_cache)
 			if(baseturf_to_replace[i])
 				baseturf_cache -= i
@@ -44,6 +44,8 @@
 	else
 		thing.PlaceOnBottom(null, baseturf)
 
+
+
 /obj/effect/baseturf_helper/space
 	name = "space baseturf editor"
 	baseturf = /turf/open/space
@@ -79,4 +81,3 @@
 /obj/effect/baseturf_helper/lava_land/surface
 	name = "lavaland baseturf editor"
 	baseturf = /turf/open/lava/smooth/lava_land_surface
-