diff --git a/spa/plugins/bluez5/backend-hsphfpd.c b/spa/plugins/bluez5/backend-hsphfpd.c
index 754f44d49..aaafef9ad 100644
--- a/spa/plugins/bluez5/backend-hsphfpd.c
+++ b/spa/plugins/bluez5/backend-hsphfpd.c
@@ -1117,6 +1117,9 @@ static DBusHandlerResult hsphfpd_parse_endpoint_properties(struct spa_bt_backend
 	else
 		t->codec = HFP_AUDIO_CODEC_CVSD;
 
+	t->n_channels = 1;
+	t->channels[0] = SPA_AUDIO_CHANNEL_MONO;
+
 	t->enabled = true;
 	spa_bt_device_connect_profile(t->device, t->profile);
 
diff --git a/spa/plugins/bluez5/backend-native.c b/spa/plugins/bluez5/backend-native.c
index db778874f..c3f5b2c5b 100644
--- a/spa/plugins/bluez5/backend-native.c
+++ b/spa/plugins/bluez5/backend-native.c
@@ -39,6 +39,7 @@
 #include <spa/support/plugin.h>
 #include <spa/utils/type.h>
 #include <spa/utils/json.h>
+#include <spa/param/audio/raw.h>
 
 #include "defs.h"
 
@@ -144,6 +145,8 @@ static struct spa_bt_transport *_transport_create(struct rfcomm *rfcomm)
 	spa_list_append(&t->device->transport_list, &t->device_link);
 	t->profile = rfcomm->profile;
 	t->backend = backend;
+	t->n_channels = 1;
+	t->channels[0] = SPA_AUDIO_CHANNEL_MONO;
 	t->enabled = true;
 
 	spa_bt_transport_add_listener(t, &rfcomm->transport_listener, &transport_events, rfcomm);
diff --git a/spa/plugins/bluez5/backend-ofono.c b/spa/plugins/bluez5/backend-ofono.c
index dfa84876d..a61b994bf 100644
--- a/spa/plugins/bluez5/backend-ofono.c
+++ b/spa/plugins/bluez5/backend-ofono.c
@@ -36,6 +36,7 @@
 #include <spa/support/dbus.h>
 #include <spa/support/plugin.h>
 #include <spa/utils/type.h>
+#include <spa/param/audio/raw.h>
 
 #include "defs.h"
 
@@ -125,6 +126,8 @@ static struct spa_bt_transport *_transport_create(struct spa_bt_backend *backend
 	t->backend = backend;
 	t->profile = profile;
 	t->codec = codec;
+	t->n_channels = 1;
+	t->channels[0] = SPA_AUDIO_CHANNEL_MONO;
 	t->enabled = true;
 
 finish: