diff --git a/memory.c b/memory.c
index 5a10fd0bde..7f1f2661a5 100644
--- a/memory.c
+++ b/memory.c
@@ -1809,7 +1809,9 @@ static void mtree_print_mr(fprintf_function mon_printf, void *f,
                    mr->alias->name,
                    mr->alias_offset,
                    mr->alias_offset
-                   + (hwaddr)int128_get64(mr->size) - 1);
+                   + (int128_nz(mr->size) ?
+                      (hwaddr)int128_get64(int128_sub(mr->size,
+                                                      int128_one())) : 0));
     } else {
         mon_printf(f,
                    TARGET_FMT_plx "-" TARGET_FMT_plx " (prio %d, %c%c): %s\n",