diff --git a/pipewire-pulseaudio/src/core-format.c b/pipewire-pulseaudio/src/core-format.c
index 94ed4cbc3..c68774895 100644
--- a/pipewire-pulseaudio/src/core-format.c
+++ b/pipewire-pulseaudio/src/core-format.c
@@ -128,14 +128,14 @@ static inline uint32_t channel_pa2id(pa_channel_position_t channel)
 	return audio_channels[channel];
 }
 
-static inline pa_channel_position_t channel_id2pa(uint32_t id)
+static inline pa_channel_position_t channel_id2pa(uint32_t id, uint32_t *aux)
 {
 	size_t i;
 	for (i = 0; i < SPA_N_ELEMENTS(audio_channels); i++) {
 		if (id == audio_channels[i])
 			return i;
 	}
-	return PA_CHANNEL_POSITION_INVALID;
+	return PA_CHANNEL_POSITION_AUX0 + (*aux)++;
 }
 
 SPA_EXPORT
@@ -362,7 +362,7 @@ int pa_format_info_to_sample_spec_fake(const pa_format_info *f, pa_sample_spec *
 int pa_format_parse_param(const struct spa_pod *param, pa_sample_spec *spec, pa_channel_map *map)
 {
 	struct spa_audio_info info = { 0 };
-	uint32_t i;
+	uint32_t i, aux;
 
 	if (param == NULL)
 		return -EINVAL;
@@ -383,13 +383,14 @@ int pa_format_parse_param(const struct spa_pod *param, pa_sample_spec *spec, pa_
 	spec->rate = info.info.raw.rate;
 	spec->channels = info.info.raw.channels;
 
+	aux = 0;
 	pa_channel_map_init(map);
 	map->channels = info.info.raw.channels;
 	for (i = 0; i < info.info.raw.channels; i++)
-		map->map[i] = channel_id2pa(info.info.raw.position[i]);
+		map->map[i] = channel_id2pa(info.info.raw.position[i], &aux);
 
 	if (!pa_channel_map_valid(map))
-		pa_channel_map_init_auto(map, info.info.raw.channels, PA_CHANNEL_MAP_DEFAULT);
+		pa_channel_map_init_extend(map, info.info.raw.channels, PA_CHANNEL_MAP_OSS);
 
 	return 0;
 }
diff --git a/pipewire-pulseaudio/src/introspect.c b/pipewire-pulseaudio/src/introspect.c
index 910cbeaf6..2c3aea589 100644
--- a/pipewire-pulseaudio/src/introspect.c
+++ b/pipewire-pulseaudio/src/introspect.c
@@ -125,7 +125,8 @@ static int sink_callback(pa_context *c, struct global *g, struct sink_data *d)
 	if (i.sample_spec.channels == g->node_info.channel_map.channels)
 		i.channel_map = g->node_info.channel_map;
 	else
-		pa_channel_map_init_auto(&i.channel_map, i.sample_spec.channels, PA_CHANNEL_MAP_OSS);
+		pa_channel_map_init_extend(&i.channel_map,
+				i.sample_spec.channels, PA_CHANNEL_MAP_OSS);
 	i.owner_module = g->id;
 	i.volume.channels = i.sample_spec.channels;
 	for (n = 0; n < i.volume.channels; n++)
@@ -855,7 +856,8 @@ static int source_callback(pa_context *c, struct global *g, struct source_data *
 	if (i.sample_spec.channels == g->node_info.channel_map.channels)
 		i.channel_map = g->node_info.channel_map;
 	else
-		pa_channel_map_init_auto(&i.channel_map, i.sample_spec.channels, PA_CHANNEL_MAP_OSS);
+		pa_channel_map_init_extend(&i.channel_map,
+				i.sample_spec.channels, PA_CHANNEL_MAP_OSS);
 	i.owner_module = g->id;
 	i.volume.channels = i.sample_spec.channels;
 	for (n = 0; n < i.volume.channels; n++)
@@ -2061,7 +2063,7 @@ static int sink_input_callback(pa_context *c, struct sink_input_data *d, struct
 		if (s->channel_map.channels == s->sample_spec.channels)
 			i.channel_map = s->channel_map;
 		else
-			pa_channel_map_init_auto(&i.channel_map,
+			pa_channel_map_init_extend(&i.channel_map,
 					i.sample_spec.channels, PA_CHANNEL_MAP_OSS);
 		i.format = s->format;
 	}
@@ -2074,7 +2076,8 @@ static int sink_input_callback(pa_context *c, struct sink_input_data *d, struct
 		if (i.sample_spec.channels == g->node_info.channel_map.channels)
 			i.channel_map = g->node_info.channel_map;
 		else
-			pa_channel_map_init_auto(&i.channel_map, i.sample_spec.channels, PA_CHANNEL_MAP_OSS);
+			pa_channel_map_init_extend(&i.channel_map,
+					i.sample_spec.channels, PA_CHANNEL_MAP_OSS);
 		ii[0].encoding = PA_ENCODING_PCM;
 		ii[0].plist = pa_proplist_new();
 		i.format = ii;
@@ -2463,7 +2466,7 @@ static int source_output_callback(struct source_output_data *d, pa_context *c, s
 		if (s->channel_map.channels == s->sample_spec.channels)
 			i.channel_map = s->channel_map;
 		else
-			pa_channel_map_init_auto(&i.channel_map,
+			pa_channel_map_init_extend(&i.channel_map,
 					i.sample_spec.channels, PA_CHANNEL_MAP_OSS);
 		i.format = s->format;
 	}
@@ -2476,7 +2479,8 @@ static int source_output_callback(struct source_output_data *d, pa_context *c, s
 		if (i.sample_spec.channels == g->node_info.channel_map.channels)
 			i.channel_map = g->node_info.channel_map;
 		else
-			pa_channel_map_init_auto(&i.channel_map, i.sample_spec.channels, PA_CHANNEL_MAP_OSS);
+			pa_channel_map_init_extend(&i.channel_map,
+					i.sample_spec.channels, PA_CHANNEL_MAP_OSS);
 		ii[0].encoding = PA_ENCODING_PCM;
 		ii[0].plist = pa_proplist_new();
 		i.format = ii;
diff --git a/pipewire-pulseaudio/src/stream.c b/pipewire-pulseaudio/src/stream.c
index b0956ddc0..b52342f1f 100644
--- a/pipewire-pulseaudio/src/stream.c
+++ b/pipewire-pulseaudio/src/stream.c
@@ -569,7 +569,8 @@ pa_stream* pa_stream_new_with_proplist(pa_context *c, const char *name,
 	pa_channel_map tmap;
 
 	if (!map)
-		PA_CHECK_VALIDITY_RETURN_NULL(c, map = pa_channel_map_init_auto(&tmap, ss->channels, PA_CHANNEL_MAP_DEFAULT), PA_ERR_INVALID);
+		PA_CHECK_VALIDITY_RETURN_NULL(c, map = pa_channel_map_init_extend(&tmap,
+					ss->channels, PA_CHANNEL_MAP_DEFAULT), PA_ERR_INVALID);
 
 	return stream_new(c, name, ss, map, NULL, 0, p);
 }
@@ -879,7 +880,7 @@ static int create_stream(pa_stream_direction_t direction,
 				continue;
 			}
 			if (pa_format_info_get_channel_map(s->req_formats[i], &chmap) < 0)
-				pa_channel_map_init_auto(&chmap, ss.channels, PA_CHANNEL_MAP_DEFAULT);
+				pa_channel_map_init_extend(&chmap, ss.channels, PA_CHANNEL_MAP_DEFAULT);
 
 			params[n_params++] = pa_format_build_param(&b, SPA_PARAM_EnumFormat,
 					&ss, &chmap);