diff --git a/code/controllers/subsystem/processing/overlays.dm b/code/controllers/subsystem/processing/overlays.dm
index 2d500b704c..2359d39498 100644
--- a/code/controllers/subsystem/processing/overlays.dm
+++ b/code/controllers/subsystem/processing/overlays.dm
@@ -45,12 +45,14 @@ PROCESSING_SUBSYSTEM_DEF(overlays)
 		fire(mc_check = FALSE)	//pair this thread up with the MC to get extra compile time
 
 /atom/proc/compile_overlays()
-	if(LAZYLEN(priority_overlays) && LAZYLEN(our_overlays))
-		overlays = our_overlays + priority_overlays
-	else if(LAZYLEN(our_overlays))
-		overlays = our_overlays
-	else if(LAZYLEN(priority_overlays))
-		overlays = priority_overlays
+	var/list/oo = our_overlays
+	var/list/po = priority_overlays
+	if(LAZYLEN(po) && LAZYLEN(oo))
+		overlays = oo + po
+	else if(LAZYLEN(oo))
+		overlays = oo
+	else if(LAZYLEN(po))
+		overlays = po
 	else
 		overlays.Cut()
 	flags &= ~OVERLAY_QUEUED