[Bug] Why should I give makerom ID when I create a cci rom?

[matiffeder]

makerom -f cci -i Main.ncch:0 -i Manual.ncch:1 -i N3DSUpdateData.ncch:6 -i UpdateData.ncch:7 -o sample.cci

When I use this command to create cci, makerom shows following error:

[SETTING ERROR] '' could not be opened
[RESULT] Invalid arguments, see 'makerom -help'

But after I use this command it will success to make a playable rom:
makerom -f cci -i Main.ncch:0:0 -i Manual.ncch:1:1 -i N3DSUpdateData.ncch:6:6 -i UpdateData.ncch:7:7 -o sample.cci

The help message said I only need <file>:<index> in cci.
It's a bug or I misunderstood something?

[jakcron]

This is a bug.