audio-extract example doesn't work on wav files

[locallycompact]

I'm trying to use the audio-extract demo to copy audio from audio file to audio file. It works when targetting an mp3, but not when targetting a wav.

lc@earthrealm ~/ffmpeg-light (master) [1]> ./result/bin/audio-extract foo.mp3 bar.mp3
bitrate : 128000
sample rate : 44100
sample format : 8
channel layout : 3
channel count : 2
AVCodecID 86017
lc@earthrealm ~/ffmpeg-light (master)> ./result/bin/audio-extract foo.mp3 bar.wav
bitrate : 128000
sample rate : 44100
sample format : 8
channel layout : 3
channel count : 2
AVCodecID 65536
audio-extract: FFmpegException "Could not open audio codec : Invalid argument"