diff -up rdesktop-1.8.0/rdpsnd_libao.c.ao rdesktop-1.8.0/rdpsnd_libao.c
--- rdesktop-1.8.0/rdpsnd_libao.c.ao	2013-06-20 14:56:16.000000000 +0200
+++ rdesktop-1.8.0/rdpsnd_libao.c	2013-08-12 00:59:55.767287517 +0200
@@ -77,6 +77,7 @@ libao_open(void)
 	format.channels = 2;
 	format.rate = 44100;
 	format.byte_format = AO_FMT_NATIVE;
+	format.matrix = NULL;
 
 	o_device = ao_open_live(default_driver, &format, NULL);
 	if (o_device == NULL)
@@ -115,6 +116,7 @@ libao_set_format(RD_WAVEFORMATEX * pwfx)
 	format.channels = pwfx->nChannels;
 	format.rate = 44100;
 	format.byte_format = AO_FMT_NATIVE;
+	format.matrix = NULL;
 
 	if (o_device != NULL)
 		ao_close(o_device);