Index: undo_old.c
===================================================================
--- undo_old.c	(revision 29074)
+++ undo_old.c	(revision 29075)
@@ -129,6 +129,7 @@
 {
 	UndoListType *slot = pcb_undo_alloc(PCB, &pcb_undo_old_oper, sizeof(UndoListType));
 
+	memset(slot, 0, sizeof(UndoListType));
 	slot->Type = CommandType;
 	slot->ID = ID;
 	slot->Kind = Kind;