Index: obj_arc.c
===================================================================
--- obj_arc.c	(revision 29722)
+++ obj_arc.c	(revision 29723)
@@ -380,7 +380,7 @@
 static const char core_arc_cookie[] = "core-arc";
 
 typedef struct {
-	pcb_arc_t *arc;
+	pcb_arc_t *arc; /* it is safe to save the object pointer because it is persistent (through the removed object list) */
 	pcb_coord_t Thickness, Clearance;
 	pcb_coord_t Width, Height;
 	pcb_coord_t X, Y;