Index: /branches/purify/source/lisp-kernel/ppc-exceptions.c
===================================================================
--- /branches/purify/source/lisp-kernel/ppc-exceptions.c	(revision 13128)
+++ /branches/purify/source/lisp-kernel/ppc-exceptions.c	(revision 13129)
@@ -1984,10 +1984,10 @@
     }
     if (need_check_memo) {
-      natural  bitnumber = area_dnode(ea, lisp_global(HEAP_START));
+      natural  bitnumber = area_dnode(ea, lisp_global(REF_BASE));
       if ((bitnumber < lisp_global(OLDSPACE_DNODE_COUNT)) &&
           ((LispObj)ea < val)) {
         atomic_set_bit(refbits, bitnumber);
         if (need_memoize_root) {
-          bitnumber = area_dnode(root, lisp_global(HEAP_START));
+          bitnumber = area_dnode(root, lisp_global(REF_BASE));
           atomic_set_bit(refbits, bitnumber);
         }