diff --git a/src/device/d-conf.c b/src/device/d-conf.c
index e57fa4b..6be89d0 100644
--- a/src/device/d-conf.c
+++ b/src/device/d-conf.c
@@ -46,6 +46,7 @@ static const char * const paths_global[] = {
 	"devices[].ttys[].tty",
 	"devices[].ttys[].rate",
 	"devices[].ttys[].initial_monitor",
+	"devices[].ttys[].lock",
 	"devices[].ttys[]",
 	"devices[]",
 };
@@ -61,6 +62,7 @@ enum enum_paths_global {
 	LEJPM_DEVICES__TTYS__TTY,
 	LEJPM_DEVICES__TTYS__RATE,
 	LEJPM_DEVICES__TTYS__INITIAL_MONITOR,
+	LEJPM_DEVICES__TTYS__LOCK,
 	LEJPM_DEVICES__TTYS,
 	LEJPM_DEVICES,
 
@@ -115,7 +117,10 @@ said_conf_global_cb(struct lejp_ctx *ctx, char reason)
 		if (!a->tty)
 			return -1;
 
+		lwsl_notice("%s: adding tty\n", __func__);
+
 		a->tty->initial_monitor = 1;
+		a->tty->lock = 1;
 		a->tty->index = (int)a->dev->ttys_owner.count;
 		lws_dll2_add_tail(&a->tty->list, &a->dev->ttys_owner);
 		return 0;
@@ -136,6 +141,11 @@ said_conf_global_cb(struct lejp_ctx *ctx, char reason)
 		a->tty->initial_monitor = 0;
 		return 0;
 	}
+	if (reason == LEJPCB_VAL_FALSE &&
+	    ctx->path_match - 1 == LEJPM_DEVICES__TTYS__LOCK) {
+		a->tty->lock = 0;
+		return 0;
+	}
 
 	if (reason != LEJPCB_VAL_STR_END)
 		return 0;
@@ -164,6 +174,7 @@ said_conf_global_cb(struct lejp_ctx *ctx, char reason)
 		break;
 	case LEJPM_DEVICES__TTYS__TTY:
 		pp = &a->tty->tty_path;
+		lwsl_notice("%s: tty path %.*s\n", __func__, (int)ctx->npos, ctx->buf);
 		break;
 
 	default:
diff --git a/src/device/d-private.h b/src/device/d-private.h
index 232b4d7..0df43a0 100644
--- a/src/device/d-private.h
+++ b/src/device/d-private.h
@@ -31,6 +31,7 @@ typedef struct sai_tty {
 	int				rate;
 	int				initial_monitor;
 	int				index;
+	int				lock;
 
 } sai_tty_t; /* owned by sai_device_t's ttys_owner */
 
diff --git a/src/device/d-sai.c b/src/device/d-sai.c
index 95097e8..be38f73 100644
--- a/src/device/d-sai.c
+++ b/src/device/d-sai.c
@@ -155,7 +155,7 @@ said_check_device(lws_sorted_usec_list_t *sul)
 				sai_tty_t *t  = lws_container_of(q,
 						    sai_tty_t, list);
 
-				if (try >= (int)LWS_ARRAY_SIZE(locked))
+				if (try >= (int)LWS_ARRAY_SIZE(locked) || !t->lock)
 					break;
 				try++;
 
@@ -209,6 +209,8 @@ said_check_device(lws_sorted_usec_list_t *sul)
 						  try);
 				setenv(p1, t->tty_path, 1);
 
+				lwsl_warn("%s: exporting %s = %s\n", __func__, p1, t->tty_path);
+
 				if (alias) {
 					p1 = strchr(alias, '=');
 					if (p1 && atoi(&p1[1]) == try) {