if (EQ (b->undo_list, Qt))
return (0);
- if (NILP (last_undo_buffer) || b != XBUFFER (last_undo_buffer))
+ if (NILP (last_undo_buffer)
+ || (BUFFER_BASE_BUFFER (b)
+ != BUFFER_BASE_BUFFER (XBUFFER (last_undo_buffer))))
{
undo_boundary (b);
XSETBUFFER (last_undo_buffer, b);