It seems that lexpr-funcall has problems with array objects: (setq a (*array nil t 10)) #T-10-70764 (apply a '(7)) NIL (lexpr-funcall a '(7)) ;((NIL 7) (NIL . 0)) TOO MANY ARGUMENTS SUPPLIED - APPLY ;BKPT WRNG-NO-ARGS I have also gotten some MPVs, but I can't seem to reproduce them.