There are 2 options on Debian/Linux: nrg2iso iat I tried nrg2iso at first, it told me the nrg file is already in ISO9660 format and did not covert. And I tried iat then that. It works fine! $ iat image.nrg image.iso Iso9660 Analyzer Tool v0.1.3 by Salvatore Santagati Licensed under GPL v2 or later Detect Signature ISO9660 START at 32768 Detect Signature ISO9660 END at 36864 Image offset start at 0 Sector header 0 bit Sector ECC 0 bit Block 2048 Done The outputed iso can be used with no wrong.