diff --git a/spa/plugins/bluez5/backend-hsphfpd.c b/spa/plugins/bluez5/backend-hsphfpd.c
index 478ff7aed..df9538569 100644
--- a/spa/plugins/bluez5/backend-hsphfpd.c
+++ b/spa/plugins/bluez5/backend-hsphfpd.c
@@ -724,8 +724,11 @@ static DBusHandlerResult hsphfpd_new_audio_connection(DBusConnection *conn, DBus
 
 fail:
 	if (r) {
-			dbus_connection_send(backend->conn, r, NULL);
-			dbus_message_unref(r);
+		DBusHandlerResult res = DBUS_HANDLER_RESULT_HANDLED;
+		if (!dbus_connection_send(backend->conn, r, NULL))
+			res = DBUS_HANDLER_RESULT_NEED_MEMORY;
+		dbus_message_unref(r);
+		return res;
 	}
 
 	return DBUS_HANDLER_RESULT_HANDLED;
@@ -1069,6 +1072,11 @@ static DBusHandlerResult hsphfpd_parse_endpoint_properties(struct impl *backend,
 	if (!endpoint->valid && endpoint->local_address && endpoint->remote_address && endpoint->profile && endpoint->role)
 		endpoint->valid = true;
 
+	if (!endpoint->remote_address || !endpoint->local_address) {
+		spa_log_debug(backend->log, NAME": Missing addresses for %s", endpoint->path);
+		return DBUS_HANDLER_RESULT_HANDLED;
+	}
+
 	d = spa_bt_device_find_by_address(backend->monitor, endpoint->remote_address, endpoint->local_address);
 	if (!d) {
 		spa_log_debug(backend->log, NAME": No device for %s", endpoint->path);
diff --git a/spa/plugins/bluez5/backend-native.c b/spa/plugins/bluez5/backend-native.c
index 5b60dfeaa..bb280dc45 100644
--- a/spa/plugins/bluez5/backend-native.c
+++ b/spa/plugins/bluez5/backend-native.c
@@ -336,7 +336,7 @@ static bool rfcomm_hfp_ag(struct spa_source *source, char* buf)
 	struct impl *backend = rfcomm->backend;
 	unsigned int features;
 	unsigned int gain;
-	unsigned int len, k, v;
+	unsigned int len;
 	unsigned int selected_codec;
 
 	if (sscanf(buf, "AT+BRSF=%u", &features) == 1) {
@@ -423,9 +423,10 @@ static bool rfcomm_hfp_ag(struct spa_source *source, char* buf)
 			if (rfcomm->transport == NULL) {
 				spa_log_warn(backend->log, NAME": can't create transport: %m");
 				// TODO: We should manage the missing transport
+			} else {
+				rfcomm->transport->codec = HFP_AUDIO_CODEC_CVSD;
+				spa_bt_device_connect_profile(rfcomm->device, rfcomm->profile);
 			}
-			rfcomm->transport->codec = HFP_AUDIO_CODEC_CVSD;
-			spa_bt_device_connect_profile(rfcomm->device, rfcomm->profile);
 		}
 
 	} else if (!rfcomm->slc_configured) {
@@ -489,21 +490,32 @@ static bool rfcomm_hfp_ag(struct spa_source *source, char* buf)
 		// We expect battery status only (bitmask 10)
         	rfcomm_send_reply(source, "+XAPL: iPhone,2");
 		rfcomm_send_reply(source, "OK");
-	} else if (sscanf(buf, "AT+IPHONEACCEV=%d", &len) == 1) {
-		if (len < 1) {
-			return false;
-		}
+	} else if (sscanf(buf, "AT+IPHONEACCEV=%u", &len) == 1) {
+		unsigned int i;
+		int k, v;
 
-		for (unsigned int i = 1; i <= len; i++) {
-			buf = strchr(buf, ',') + 1;
-			if (sscanf(buf, "%d", &k) != 1) return false;
-			buf = strchr(buf, ',') + 1;
-			if (sscanf(buf, "%d", &v) != 1) return false;
+		if (len < 1 || len > 100)
+			return false;
+
+		for (i = 1; i <= len; i++) {
+			buf = strchr(buf, ',');
+			if (buf == NULL)
+				return false;
+			++buf;
+			if (sscanf(buf, "%d", &k) != 1)
+				return false;
+
+			buf = strchr(buf, ',');
+			if (buf == NULL)
+				return false;
+			++buf;
+			if (sscanf(buf, "%d", &v) != 1)
+				return false;
 
 			if (k == SPA_BT_HFP_HF_IPHONEACCEV_KEY_BATTERY) {
 				// Battery level is reported in range of 0-9, convert to 0-100%
-				uint8_t level = (v + 1) * 10;
-				spa_log_debug(backend->log, NAME": battery level: %d%%", level);
+				uint8_t level = (SPA_CLAMP(v, 0, 9) + 1) * 10;
+				spa_log_debug(backend->log, NAME": battery level: %d%%", (int)level);
 
 				// TODO: report without Battery Provider (using props)
 				spa_bt_device_report_battery_level(rfcomm->device, level);
@@ -625,9 +637,10 @@ static bool rfcomm_hfp_hf(struct spa_source *source, char* buf)
 						if (rfcomm->transport == NULL) {
 							spa_log_warn(backend->log, NAME": can't create transport: %m");
 							// TODO: We should manage the missing transport
+						} else {
+							rfcomm->transport->codec = HFP_AUDIO_CODEC_CVSD;
+							spa_bt_device_connect_profile(rfcomm->device, rfcomm->profile);
 						}
-						rfcomm->transport->codec = HFP_AUDIO_CODEC_CVSD;
-						spa_bt_device_connect_profile(rfcomm->device, rfcomm->profile);
 					}
 					break;
 				default:
diff --git a/spa/plugins/bluez5/backend-ofono.c b/spa/plugins/bluez5/backend-ofono.c
index a761070c6..2f0781194 100644
--- a/spa/plugins/bluez5/backend-ofono.c
+++ b/spa/plugins/bluez5/backend-ofono.c
@@ -351,6 +351,11 @@ static DBusHandlerResult ofono_audio_card_found(struct impl *backend, char *path
 		close(fd);
 	}
 
+	if (!remote_address || !local_address) {
+		spa_log_error(backend->log, NAME": Missing addresses for %s", path);
+		return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
+	}
+
 	d = spa_bt_device_find_by_address(backend->monitor, remote_address, local_address);
 	if (!d) {
 		spa_log_error(backend->log, NAME": Device doesn’t exist for %s", path);
@@ -449,8 +454,11 @@ static DBusHandlerResult ofono_new_audio_connection(DBusConnection *conn, DBusMe
 
 fail:
 	if (r) {
-			dbus_connection_send(backend->conn, r, NULL);
-			dbus_message_unref(r);
+		DBusHandlerResult res = DBUS_HANDLER_RESULT_HANDLED;
+		if (!dbus_connection_send(backend->conn, r, NULL))
+			res = DBUS_HANDLER_RESULT_NEED_MEMORY;
+		dbus_message_unref(r);
+		return res;
 	}
 
 	return DBUS_HANDLER_RESULT_HANDLED;
diff --git a/spa/plugins/bluez5/bluez5-device.c b/spa/plugins/bluez5/bluez5-device.c
index 64afd5a48..f6cbb4eda 100644
--- a/spa/plugins/bluez5/bluez5-device.c
+++ b/spa/plugins/bluez5/bluez5-device.c
@@ -1474,6 +1474,9 @@ static int impl_set_param(void *object,
 		uint32_t profile;
 		enum spa_bluetooth_audio_codec codec;
 
+		if (param == NULL)
+			return -EINVAL;
+
 		if ((res = spa_pod_parse_object(param,
 				SPA_TYPE_OBJECT_ParamProfile, NULL,
 				SPA_PARAM_PROFILE_index, SPA_POD_Int(&id))) < 0) {
@@ -1496,6 +1499,9 @@ static int impl_set_param(void *object,
 		struct spa_pod *props = NULL;
 		struct node *node;
 
+		if (param == NULL)
+			return -EINVAL;
+
 		if ((res = spa_pod_parse_object(param,
 				SPA_TYPE_OBJECT_ParamRoute, NULL,
 				SPA_PARAM_ROUTE_index, SPA_POD_Int(&id),
diff --git a/spa/plugins/bluez5/sco-source.c b/spa/plugins/bluez5/sco-source.c
index 480c3a3ce..b1adc0a0a 100644
--- a/spa/plugins/bluez5/sco-source.c
+++ b/spa/plugins/bluez5/sco-source.c
@@ -692,7 +692,7 @@ static int impl_node_send_command(void *object, const struct spa_command *comman
 
 static void emit_node_info(struct impl *this, bool full)
 {
-	bool is_ag = (this->transport->profile & SPA_BT_PROFILE_HEADSET_AUDIO_GATEWAY);
+	bool is_ag = this->transport && (this->transport->profile & SPA_BT_PROFILE_HEADSET_AUDIO_GATEWAY);
 	struct spa_dict_item ag_node_info_items[] = {
 		{ SPA_KEY_DEVICE_API, "bluez5" },
 		{ SPA_KEY_MEDIA_CLASS, "Stream/Output/Audio" },