Can anybody tell me what tools produce MP3 files that work correctly when using SegaCD games?

I just tried to play my sonic cd, but the game exits after the "sega" splashscreen when mp3 files are present. If I remove the mp3 files, sonic CD runs fine (but without music).

I ripped the audiotracks to wav files, and then converted them to mp3 using lame (on my linux machine)
lame track_01.wav

and after that renamed the files to sonic.iso and sonic_01.mp3 etc.
But those mp3 files do not seem to work and exit picodrive (they play fine on the N900 media player)