"Audio encoding failed" when converting flv to mp3

Binary package hint: ffmpeg

I have ffmpeg 4:0.5+svn20090706-2ubuntu1 and libavcodec-unstripped-52 installed. Trying to convert flv to mp3, I get the following messages (note that the conversion actually works, I get a valid mp3 file but there is still those error messages):

FFmpeg version SVN-r19352-4:0.5+svn20090706-2ubuntu1, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --extra-version=4:0.5+svn20090706-2ubuntu1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --disable-stripping --disable-vhook --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --extra-cflags=-I/build/buildd/ffmpeg-0.5+svn20090706/debian/include --enable-shared --disable-static
  libavutil 49.15. 0 / 49.15. 0
  libavcodec 52.20. 0 / 52.20. 0
  libavformat 52.31. 0 / 52.31. 0
  libavdevice 52. 1. 0 / 52. 1. 0
  libavfilter 0. 4. 0 / 0. 4. 0
  libswscale 0. 7. 1 / 0. 7. 1
  libpostproc 51. 2. 0 / 51. 2. 0
  built on Aug 26 2009 09:45:50, gcc: 4.4.1

Seems stream 0 codec frame rate differs from container frame rate: 50.00 (50/1) -> 25.00 (25/1)
Input #0, flv, from 'reincke.flv':
  Duration: 00:03:36.36, start: 0.000000, bitrate: 32 kb/s
    Stream #0.0: Video: h264, yuv420p, 320x240 [PAR 1:1 DAR 4:3], 32 kb/s, 25 tbr, 1k tbn, 50 tbc
    Stream #0.1: Audio: aac, 22050 Hz, stereo, s16
Output #0, mp3, to 'reincke.mp3':
    Stream #0.0: Audio: libmp3lame, 22050 Hz, stereo, s16, 64 kb/s
Stream mapping:
  Stream #0.1 -> #0.0
Press [q] to stop encoding
[libmp3lame @ 0xa0474d0]lame: output buffer too small (buffer index: 9404, free bytes: 388)
Audio encoding failed