IndexError: list index out of range

[HuyWon]

Please help me fix this error, i did it on mac cathanila and iphone 5s 6.1. I would like to thank

Vieux - A tool for 32/64 Bit OTA downgrades

Current version is: 1.0.1
If you are using a 64 Bit device then connect it in DFU Mode
If you are using a 32 Bit device then just have it connected in NORMAL mode
Files cleaned.
Traceback (most recent call last):
File "./vieux", line 89, in
ipsw.unzipIPSW(argv[2])
IndexError: list index out of range
joker@Jokers-MacBook-Pro Vieux-master %