diff --git a/audio/out/ao_alsa.c b/audio/out/ao_alsa.c
index 30d0f249b9..75a11a85c3 100644
--- a/audio/out/ao_alsa.c
+++ b/audio/out/ao_alsa.c
@@ -275,6 +275,7 @@ static const int alsa_to_mp_channels[][2] = {
     {SND_CHMAP_RLC,     MP_SP(SDL)},
     {SND_CHMAP_MONO,    MP_SP(FC)},
     {SND_CHMAP_NA,      MP_SPEAKER_ID_NA},
+    {SND_CHMAP_UNKNOWN, MP_SPEAKER_ID_NA},
     {SND_CHMAP_LAST,    MP_SPEAKER_ID_COUNT}
 };