diff --git a/hardware/colead-slm/api.c b/hardware/colead-slm/api.c
index 7ae2892b..b4755ee7 100644
--- a/hardware/colead-slm/api.c
+++ b/hardware/colead-slm/api.c
@@ -51,6 +51,7 @@ static int clear_instances(void)
 	struct sr_dev_inst *sdi;
 	struct drv_context *drvc;
 	struct dev_context *devc;
+	struct sr_serial_dev_inst *serial;
 	GSList *l;
 
 	if (!(drvc = di->priv))
@@ -61,7 +62,8 @@ static int clear_instances(void)
 			continue;
 		if (!(devc = sdi->priv))
 			continue;
-		sr_serial_dev_inst_free(devc->serial);
+		serial = sdi->conn;
+		sr_serial_dev_inst_free(serial);
 		sr_dev_inst_free(sdi);
 	}
 	g_slist_free(drvc->instances);
@@ -116,9 +118,10 @@ static GSList *hw_scan(GSList *options)
 		return NULL;
 	}
 
-	if (!(devc->serial = sr_serial_dev_inst_new(conn, serialcomm)))
+	if (!(sdi->conn = sr_serial_dev_inst_new(conn, serialcomm)))
 		return NULL;
 
+	sdi->inst_type = SR_INST_SERIAL;
 	sdi->priv = devc;
 	sdi->driver = di;
 	if (!(probe = sr_probe_new(0, SR_PROBE_ANALOG, TRUE, "P1")))
@@ -137,14 +140,10 @@ static GSList *hw_dev_list(void)
 
 static int hw_dev_open(struct sr_dev_inst *sdi)
 {
-	struct dev_context *devc;
+	struct sr_serial_dev_inst *serial;
 
-	if (!(devc = sdi->priv)) {
-		sr_err("sdi->priv was NULL.");
-		return SR_ERR_BUG;
-	}
-
-	if (serial_open(devc->serial, SERIAL_RDWR) != SR_OK)
+	serial = sdi->conn;
+	if (serial_open(serial, SERIAL_RDWR) != SR_OK)
 		return SR_ERR;
 
 	sdi->status = SR_ST_ACTIVE;
@@ -154,12 +153,11 @@ static int hw_dev_open(struct sr_dev_inst *sdi)
 
 static int hw_dev_close(struct sr_dev_inst *sdi)
 {
-	struct dev_context *devc;
+	struct sr_serial_dev_inst *serial;
 
-	devc = sdi->priv;
-
-	if (devc->serial && devc->serial->fd != -1) {
-		serial_close(devc->serial);
+	serial = sdi->conn;
+	if (serial && serial->fd != -1) {
+		serial_close(serial);
 		sdi->status = SR_ST_INACTIVE;
 	}
 
@@ -233,6 +231,7 @@ static int hw_dev_acquisition_start(const struct sr_dev_inst *sdi,
 				    void *cb_data)
 {
 	struct dev_context *devc;
+	struct sr_serial_dev_inst *serial;
 
 	if (!(devc = sdi->priv)) {
 		sr_err("sdi->priv was NULL.");
@@ -245,7 +244,8 @@ static int hw_dev_acquisition_start(const struct sr_dev_inst *sdi,
 	std_session_send_df_header(cb_data, DRIVER_LOG_DOMAIN);
 
 	/* Poll every 150ms, or whenever some data comes in. */
-	sr_source_add(devc->serial->fd, G_IO_IN, 150, colead_slm_receive_data,
+	serial = sdi->conn;
+	sr_source_add(serial->fd, G_IO_IN, 150, colead_slm_receive_data,
 			(void *)sdi);
 
 	return SR_OK;
@@ -254,7 +254,7 @@ static int hw_dev_acquisition_start(const struct sr_dev_inst *sdi,
 static int hw_dev_acquisition_stop(struct sr_dev_inst *sdi, void *cb_data)
 {
 	return std_hw_dev_acquisition_stop_serial(sdi, cb_data, hw_dev_close,
-	       ((struct dev_context *)(sdi->priv))->serial, DRIVER_LOG_DOMAIN);
+	       sdi->conn, DRIVER_LOG_DOMAIN);
 }
 
 SR_PRIV struct sr_dev_driver colead_slm_driver_info = {
diff --git a/hardware/colead-slm/protocol.c b/hardware/colead-slm/protocol.c
index d14a382b..9a9d10c8 100644
--- a/hardware/colead-slm/protocol.c
+++ b/hardware/colead-slm/protocol.c
@@ -181,6 +181,7 @@ SR_PRIV int colead_slm_receive_data(int fd, int revents, void *cb_data)
 {
 	const struct sr_dev_inst *sdi;
 	struct dev_context *devc;
+	struct sr_serial_dev_inst *serial;
 	int len;
 	char buf[128];
 
@@ -196,21 +197,22 @@ SR_PRIV int colead_slm_receive_data(int fd, int revents, void *cb_data)
 		/* Timeout event. */
 		return TRUE;
 
+	serial = sdi->conn;
 	if (devc->state == IDLE) {
-		if (serial_read(devc->serial, buf, 128) != 1 || buf[0] != 0x10)
+		if (serial_read(serial, buf, 128) != 1 || buf[0] != 0x10)
 			/* Nothing there, or caught the tail end of a previous packet,
 			 * or some garbage. Unless it's a single "data ready" byte,
 			 * we don't want it. */
 			return TRUE;
 		/* Got 0x10, "measurement ready". */
-		if (serial_write(devc->serial, "\x20", 1) == -1)
+		if (serial_write(serial, "\x20", 1) == -1)
 			sr_err("unable to send command: %s", strerror(errno));
 		else {
 			devc->state = COMMAND_SENT;
 			devc->buflen = 0;
 		}
 	} else {
-		len = serial_read(devc->serial, devc->buf + devc->buflen,
+		len = serial_read(serial, devc->buf + devc->buflen,
 				10 - devc->buflen);
 		if (len < 1)
 			return TRUE;
diff --git a/hardware/colead-slm/protocol.h b/hardware/colead-slm/protocol.h
index 0e37cd95..84d65117 100644
--- a/hardware/colead-slm/protocol.h
+++ b/hardware/colead-slm/protocol.h
@@ -51,7 +51,6 @@ struct dev_context {
 
 	/** The current number of already received samples. */
 	uint64_t num_samples;
-	struct sr_serial_dev_inst *serial;
 	int state;
 	char buf[10];
 	int buflen;