diff --git a/spa/plugins/bluez5/a2dp-sink.c b/spa/plugins/bluez5/a2dp-sink.c
index 38dd1f292..34d45f377 100644
--- a/spa/plugins/bluez5/a2dp-sink.c
+++ b/spa/plugins/bluez5/a2dp-sink.c
@@ -361,6 +361,8 @@ static int send_buffer(struct impl *this)
 	struct rtp_header *header;
 	struct rtp_payload *payload;
 
+	spa_return_val_if_fail(this->transport, -EIO);
+
 	header = (struct rtp_header *)this->buffer;
 	payload = (struct rtp_payload *)(this->buffer + sizeof(struct rtp_header));
 	memset(this->buffer, 0, sizeof(struct rtp_header)+sizeof(struct rtp_payload));
@@ -487,6 +489,8 @@ static int set_bitpool(struct impl *this, int bitpool)
 {
 	struct port *port = &this->port;
 
+	spa_return_val_if_fail(this->transport, -EIO);
+
 	if (bitpool < this->min_bitpool)
 		bitpool = this->min_bitpool;
 	if (bitpool > this->max_bitpool)
@@ -715,7 +719,11 @@ static void a2dp_on_timeout(struct spa_source *source)
 static int init_sbc(struct impl *this)
 {
         struct spa_bt_transport *transport = this->transport;
-	a2dp_sbc_t *conf = transport->configuration;
+	a2dp_sbc_t *conf;
+
+	spa_return_val_if_fail(transport, -EIO);
+
+	conf = transport->configuration;
 
 	sbc_init(&this->sbc, 0);
 	this->sbc.endian = SBC_LE;
@@ -797,6 +805,8 @@ static int do_start(struct impl *this)
 	if (this->started)
 		return 0;
 
+	spa_return_val_if_fail(this->transport, -EIO);
+
 	this->following = is_following(this);
 
         spa_log_debug(this->log, NAME " %p: start following:%d", this, this->following);
@@ -1039,6 +1049,8 @@ impl_node_port_enum_params(void *object, int seq,
 	case SPA_PARAM_EnumFormat:
 		if (result.index > 0)
 			return 0;
+		if (this->transport == NULL)
+			return -EIO;
 
 		switch (this->transport->codec) {
 		case A2DP_CODEC_SBC:
diff --git a/spa/plugins/bluez5/a2dp-source.c b/spa/plugins/bluez5/a2dp-source.c
index 16e35fce9..c36927b18 100644
--- a/spa/plugins/bluez5/a2dp-source.c
+++ b/spa/plugins/bluez5/a2dp-source.c
@@ -408,6 +408,10 @@ static void a2dp_on_ready_read(struct spa_source *source)
 		spa_log_error(this->log, "source is not an input, rmask=%d", source->rmask);
 		goto stop;
 	}
+	if (this->transport == NULL) {
+		spa_log_debug(this->log, "no transport, stop reading");
+		goto stop;
+	}
 
 	/* update the current pts */
 	spa_system_clock_gettime(this->data_system, CLOCK_MONOTONIC, &this->now);
@@ -494,11 +498,10 @@ static int do_start(struct impl *this)
 	if (this->started)
 		return 0;
 
-	if (this->transport == NULL)
-		return -EIO;
-
 	spa_log_debug(this->log, NAME" %p: start", this);
 
+	spa_return_val_if_fail(this->transport != NULL, -EIO);
+
 	if (this->transport->state >= SPA_BT_TRANSPORT_STATE_PENDING)
 		res = transport_start(this);
 
@@ -693,7 +696,6 @@ impl_node_port_enum_params(void *object, int seq,
 	case SPA_PARAM_EnumFormat:
 		if (result.index > 0)
 			return 0;
-
 		if (this->transport == NULL)
 			return -EIO;
 
diff --git a/spa/plugins/bluez5/sco-sink.c b/spa/plugins/bluez5/sco-sink.c
index ffb0cc732..5dd22fbda 100644
--- a/spa/plugins/bluez5/sco-sink.c
+++ b/spa/plugins/bluez5/sco-sink.c
@@ -130,6 +130,7 @@ struct impl {
 
 	/* Counts */
 	uint64_t sample_count;
+	uint32_t write_mtu;
 };
 
 #define NAME "sco-sink"
@@ -347,7 +348,7 @@ static int impl_node_set_param(void *object, uint32_t id, uint32_t flags,
 static bool write_data(struct impl *this, const uint8_t *data, uint32_t size, uint32_t *total_written)
 {
 	uint32_t local_total_written = 0;
-	const uint32_t mtu_size = this->transport->write_mtu;
+	const uint32_t mtu_size = this->write_mtu;
 
 	while (local_total_written <= (size - mtu_size)) {
 		const int bytes_written = write(this->sock_fd, data, mtu_size);
@@ -414,28 +415,29 @@ static int render_buffers(struct impl *this, uint64_t now_time)
 	return 0;
 }
 
-static void fill_socket (struct impl *this)
+static void fill_socket(struct impl *this)
 {
-  struct port *port = &this->port;
-  static const uint8_t zero_buffer[1024 * 4] = { 0, };
-  uint32_t fill_size = this->transport->write_mtu;
-  uint32_t fills = 0;
-  uint32_t total_written = 0;
+	struct port *port = &this->port;
+	static const uint8_t zero_buffer[1024 * 4] = { 0, };
+	uint32_t fill_size = this->write_mtu;
+	uint32_t fills = 0;
+	uint32_t total_written = 0;
 
-  /* Fill the socked */
-  while (fills < FILL_FRAMES) {
-          uint32_t written = 0;
 
-          /* Write the data */
-          if (!write_data(this, zero_buffer, fill_size, &written))
-                  break;
+	/* Fill the socket */
+	while (fills < FILL_FRAMES) {
+		uint32_t written = 0;
 
-          total_written += written;
-          fills++;
-  }
+		/* Write the data */
+		if (!write_data(this, zero_buffer, fill_size, &written))
+			break;
 
-  /* Update the sample count */
-  this->sample_count += total_written / port->frame_size;
+		total_written += written;
+		fills++;
+	}
+
+	/* Update the sample count */
+	this->sample_count += total_written / port->frame_size;
 }
 
 static void sco_on_flush(struct spa_source *source)
@@ -479,7 +481,7 @@ static void sco_on_timeout(struct spa_source *source)
 
 	/* If this is the first timeout, set the start time and fill the socked */
 	if (this->start_time == 0) {
-		fill_socket (this);
+		fill_socket(this);
 		this->start_time = now_time;
 	}
 
@@ -503,7 +505,7 @@ static int do_start(struct impl *this)
 		return 0;
 
 	/* Make sure the transport is valid */
-	spa_return_val_if_fail (this->transport != NULL, -EIO);
+	spa_return_val_if_fail(this->transport != NULL, -EIO);
 
 	/* Set the following flag */
 	this->following = is_following(this);
@@ -517,6 +519,7 @@ static int do_start(struct impl *this)
 		return -1;
 
 	/* Set the write MTU */
+	this->write_mtu = this->transport->write_mtu;
 	val = FILL_FRAMES * this->transport->write_mtu;
 	if (setsockopt(this->sock_fd, SOL_SOCKET, SO_SNDBUF, &val, sizeof(val)) < 0)
 		spa_log_warn(this->log, "sco-sink %p: SO_SNDBUF %m", this);
diff --git a/spa/plugins/bluez5/sco-source.c b/spa/plugins/bluez5/sco-source.c
index 065a27e44..b9e803a3f 100644
--- a/spa/plugins/bluez5/sco-source.c
+++ b/spa/plugins/bluez5/sco-source.c
@@ -117,6 +117,7 @@ struct impl {
 
 	struct timespec now;
 	uint32_t sample_count;
+	uint32_t read_mtu;
 };
 
 #define NAME "sco-source"
@@ -294,8 +295,9 @@ static void reset_buffers(struct port *port)
 	}
 }
 
-static bool read_data(struct impl *this, uint8_t *data, uint32_t size, uint32_t *total_read) {
-	const uint32_t mtu_size = this->transport->read_mtu;
+static bool read_data(struct impl *this, uint8_t *data, uint32_t size, uint32_t *total_read)
+{
+	const uint32_t mtu_size = this->read_mtu;
 	uint32_t local_total_read = 0;
 
 	/* Read chunks of mtu_size */
@@ -321,7 +323,7 @@ static bool read_data(struct impl *this, uint8_t *data, uint32_t size, uint32_t
 
 done:
 	if (total_read)
-	  *total_read = local_total_read;
+		*total_read = local_total_read;
 	return true;
 }
 
@@ -428,7 +430,8 @@ static int do_start(struct impl *this)
 		spa_log_warn(this->log, "sco-source %p: SO_SNDBUF %m", this);
 
 	/* Set the read MTU */
-	val = FILL_FRAMES * this->transport->read_mtu;
+	this->read_mtu = this->transport->read_mtu;
+	val = FILL_FRAMES * this->read_mtu;
 	if (setsockopt(this->sock_fd, SOL_SOCKET, SO_RCVBUF, &val, sizeof(val)) < 0)
 		spa_log_warn(this->log, "sco-source %p: SO_RCVBUF %m", this);
 
@@ -644,7 +647,6 @@ impl_node_port_enum_params(void *object, int seq,
 	case SPA_PARAM_EnumFormat:
 		if (result.index > 0)
 			return 0;
-
 		if (this->transport == NULL)
 			return -EIO;