defer base64BufPool.Put(tokenBuf)

	token := *tokenBuf
	// Copy token to buffer, truncate to length.
	token = token[:copy(token[:base64BufferSize], tokenStr)]

	signer, err := ParseUnverifiedStandardClaims(token, claims, *bufp)
	if err != nil {
		return err
	}

	i := bytes.LastIndexByte(token, '.')
	if i < 0 {
		return jwtgo.ErrSignatureInvalid
	}