diff --git a/spa/plugins/alsa/acp/acp.c b/spa/plugins/alsa/acp/acp.c
index aadb1277d..c2ab555f0 100644
--- a/spa/plugins/alsa/acp/acp.c
+++ b/spa/plugins/alsa/acp/acp.c
@@ -16,7 +16,8 @@ void *_acp_log_data;
 
 struct spa_i18n *acp_i18n;
 
-#define DEFAULT_RATE	48000
+#define DEFAULT_CHANNELS	256u
+#define DEFAULT_RATE		48000u
 
 #define VOLUME_ACCURACY (PA_VOLUME_NORM/100)  /* don't require volume adjustments to be perfectly correct. don't necessarily extend granularity in software unless the differences get greater than this level */
 
@@ -183,6 +184,7 @@ static void device_free(void *data)
 	pa_dynarray_clear(&dev->port_array);
 	pa_proplist_free(dev->proplist);
 	pa_hashmap_free(dev->ports);
+	free(dev->device.format.map);
 }
 
 static inline void channelmap_to_acp(pa_channel_map *m, uint32_t *map)
@@ -213,9 +215,10 @@ static void init_device(pa_card *impl, pa_alsa_device *dev, pa_alsa_direction_t
 	dev->device.format.format_mask = m->sample_spec.format;
 	dev->device.format.rate_mask = m->sample_spec.rate;
 	dev->device.format.channels = m->channel_map.channels;
+	dev->device.format.map = calloc(m->channel_map.channels, sizeof(uint32_t));
+	channelmap_to_acp(&m->channel_map, dev->device.format.map);
 	pa_cvolume_reset(&dev->real_volume, dev->device.format.channels);
 	pa_cvolume_reset(&dev->soft_volume, dev->device.format.channels);
-	channelmap_to_acp(&m->channel_map, dev->device.format.map);
 	dev->direction = direction;
 	dev->proplist = pa_proplist_new();
 	pa_proplist_update(dev->proplist, PA_UPDATE_REPLACE, m->proplist);
@@ -1777,7 +1780,7 @@ struct acp_card *acp_card_new(uint32_t index, const struct acp_dict *props)
 	impl->auto_port = true;
 	impl->ignore_dB = false;
 	impl->rate = DEFAULT_RATE;
-	impl->pro_channels = ACP_MAX_CHANNELS;
+	impl->pro_channels = DEFAULT_CHANNELS;
 
 	if (props) {
 		if ((s = acp_dict_lookup(props, "api.alsa.use-ucm")) != NULL)
diff --git a/spa/plugins/alsa/acp/acp.h b/spa/plugins/alsa/acp/acp.h
index 4b9f2c495..01ad11806 100644
--- a/spa/plugins/alsa/acp/acp.h
+++ b/spa/plugins/alsa/acp/acp.h
@@ -24,7 +24,6 @@ extern "C" {
 #endif
 
 #define ACP_INVALID_INDEX	((uint32_t)-1)
-#define ACP_MAX_CHANNELS	64
 
 struct acp_dict_item {
 	const char *key;
@@ -93,7 +92,7 @@ struct acp_format {
 	uint32_t format_mask;
 	uint32_t rate_mask;
 	uint32_t channels;
-	uint32_t map[ACP_MAX_CHANNELS];
+	uint32_t *map;
 };
 
 #define ACP_DICT_INIT(items,n_items) ((struct acp_dict) { 0, (n_items), (items) })
diff --git a/spa/plugins/alsa/alsa-acp-device.c b/spa/plugins/alsa/alsa-acp-device.c
index 5d46feed4..4d8a6d92d 100644
--- a/spa/plugins/alsa/alsa-acp-device.c
+++ b/spa/plugins/alsa/alsa-acp-device.c
@@ -671,8 +671,8 @@ static int apply_device_props(struct impl *this, struct acp_device *dev, struct
 	struct spa_pod_prop *prop;
 	struct spa_pod_object *obj = (struct spa_pod_object *) props;
 	int changed = 0;
-	float volumes[ACP_MAX_CHANNELS];
-	uint32_t channels[ACP_MAX_CHANNELS];
+	float volumes[SPA_AUDIO_MAX_CHANNELS];
+	uint32_t channels[SPA_AUDIO_MAX_CHANNELS];
 	uint32_t n_volumes = 0;
 
 	if (!spa_pod_is_object_type(props, SPA_TYPE_OBJECT_Props))
@@ -694,13 +694,13 @@ static int apply_device_props(struct impl *this, struct acp_device *dev, struct
 			break;
 		case SPA_PROP_channelVolumes:
 			if ((n_volumes = spa_pod_copy_array(&prop->value, SPA_TYPE_Float,
-					volumes, ACP_MAX_CHANNELS)) > 0) {
+					volumes, SPA_AUDIO_MAX_CHANNELS)) > 0) {
 				changed++;
 			}
 			break;
 		case SPA_PROP_channelMap:
 			if (spa_pod_copy_array(&prop->value, SPA_TYPE_Id,
-					channels, ACP_MAX_CHANNELS) > 0) {
+					channels, SPA_AUDIO_MAX_CHANNELS) > 0) {
 				changed++;
 			}
 			break;