diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
index 07e839e..b10154c 100644
--- a/arch/um/drivers/net_kern.c
+++ b/arch/um/drivers/net_kern.c
@@ -498,10 +498,8 @@
 	int index;
 };
 
-/* Filled in at boot time.  Will need locking if the transports become
- * modular.
- */
-struct list_head transports = LIST_HEAD_INIT(transports);
+static DEFINE_SPINLOCK(transports_lock);
+static LIST_HEAD(transports);
 
 /* Filled in during early boot */
 struct list_head eth_cmd_line = LIST_HEAD_INIT(eth_cmd_line);
@@ -540,7 +538,10 @@
 	char *mac = NULL;
 	int match;
 
+	spin_lock(&transports_lock);
+	BUG_ON(!list_empty(&new->list));
 	list_add(&new->list, &transports);
+	spin_unlock(&transports_lock);
 
 	list_for_each_safe(ele, next, &eth_cmd_line){
 		eth = list_entry(ele, struct eth_init, list);