1 files changed, 2 insertions, 1 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 43befd722bb..f679787e95c 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -5619,7 +5619,8 @@ mark_buffer (Lisp_Object buf)
   /* buffer-local Lisp variables start at `undo_list',
      tho only the ones from `name' on are GC'd normally.  */
   for (ptr = &buffer->BUFFER_INTERNAL_FIELD (name);
-       (char *)ptr < (char *)buffer + sizeof (struct buffer);
+       ptr <= &PER_BUFFER_VALUE (buffer,
+                                 PER_BUFFER_VAR_OFFSET (LAST_FIELD_PER_BUFFER));
        ptr++)
     mark_object (*ptr);