MP3 lump identified as "Unknown"

[iid]

Archive: http://www.doomworld.com/idgames/?id=16172
File: fm5_dh.wad
Lump: D_RUNNIN
It is an MP3 file. Identified as "Unknown".

[iid]

Same issue with a few lumps from DVII-1u.wad, namely, the first 417 bytes are zeros and the first valid MP3 frame starts at offset 417. (417 is a size of an MP3 frame if sample rate is 44100 and bitrate is 128 kbps, which is often the case in wads). I think that the detection should be fixed.