diff --git a/src/include/ipxe/neighbour.h b/src/include/ipxe/neighbour.h
index 1ca0ee333..7e7fac277 100644
--- a/src/include/ipxe/neighbour.h
+++ b/src/include/ipxe/neighbour.h
@@ -49,9 +49,9 @@ struct neighbour {
 	/** Link-layer destination address */
 	uint8_t ll_dest[MAX_LL_ADDR_LEN];
 
-	/** Neighbour discovery protocol (if any) */
+	/** Neighbour discovery protocol (if discovery is ongoing) */
 	struct neighbour_discovery *discovery;
-	/** Network-layer source address (if any) */
+	/** Network-layer source address (for discovery requests) */
 	uint8_t net_source[MAX_NET_ADDR_LEN];
 	/** Retransmission timer */
 	struct retry_timer timer;
@@ -60,17 +60,6 @@ struct neighbour {
 	struct list_head tx_queue;
 };
 
-/**
- * Test if neighbour cache entry has a valid link-layer address
- *
- * @v neighbour		Neighbour cache entry
- * @ret has_ll_dest	Neighbour cache entry has a valid link-layer address
- */
-static inline __attribute__ (( always_inline )) int
-neighbour_has_ll_dest ( struct neighbour *neighbour ) {
-	return ( ! timer_running ( &neighbour->timer ) );
-}
-
 extern struct list_head neighbours;
 
 extern int neighbour_tx ( struct io_buffer *iobuf, struct net_device *netdev,
diff --git a/src/net/neighbour.c b/src/net/neighbour.c
index 253cdc0e6..908f8e4b2 100644
--- a/src/net/neighbour.c
+++ b/src/net/neighbour.c
@@ -186,6 +186,9 @@ static void neighbour_discovered ( struct neighbour *neighbour,
 	/* Stop retransmission timer */
 	stop_timer ( &neighbour->timer );
 
+	/* Mark discovery as complete */
+	neighbour->discovery = NULL;
+
 	/* Transmit any packets in queue.  Take out a temporary
 	 * reference on the entry to prevent it from going out of
 	 * scope during the call to net_tx().
@@ -300,6 +303,7 @@ int neighbour_tx ( struct io_buffer *iobuf, struct net_device *netdev,
 		   struct neighbour_discovery *discovery,
 		   const void *net_source ) {
 	struct neighbour *neighbour;
+	int rc;
 
 	/* Find or create neighbour cache entry */
 	neighbour = neighbour_find ( netdev, net_protocol, net_dest );
@@ -310,19 +314,24 @@ int neighbour_tx ( struct io_buffer *iobuf, struct net_device *netdev,
 		neighbour_discover ( neighbour, discovery, net_source );
 	}
 
-	/* If a link-layer address is available then transmit
-	 * immediately, otherwise queue for later transmission.
+	/* If discovery is still in progress then queue for later
+	 * transmission.
 	 */
-	if ( neighbour_has_ll_dest ( neighbour ) ) {
-		return net_tx ( iobuf, netdev, net_protocol, neighbour->ll_dest,
-				netdev->ll_addr );
-	} else {
+	if ( neighbour->discovery ) {
 		DBGC2 ( neighbour, "NEIGHBOUR %s %s %s deferring packet\n",
 			netdev->name, net_protocol->name,
 			net_protocol->ntoa ( net_dest ) );
 		list_add_tail ( &iobuf->list, &neighbour->tx_queue );
 		return 0;
 	}
+
+	/* Otherwise, transmit immediately */
+	if ( ( rc = net_tx ( iobuf, netdev, net_protocol, neighbour->ll_dest,
+			     netdev->ll_addr ) ) != 0 ) {
+		return rc;
+	}
+
+	return 0;
 }
 
 /**
diff --git a/src/usr/neighmgmt.c b/src/usr/neighmgmt.c
index 9fd88f82b..fcdcbbfbb 100644
--- a/src/usr/neighmgmt.c
+++ b/src/usr/neighmgmt.c
@@ -50,9 +50,8 @@ void nstat ( void ) {
 		printf ( "%s %s %s is %s %s", netdev->name, net_protocol->name,
 			 net_protocol->ntoa ( neighbour->net_dest ),
 			 ll_protocol->name,
-			 ( neighbour_has_ll_dest ( neighbour ) ?
-			   ll_protocol->ntoa ( neighbour->ll_dest ) :
-			   "(incomplete)" ) );
+			 ( neighbour->discovery ? "(incomplete)" :
+			   ll_protocol->ntoa ( neighbour->ll_dest ) ) );
 		if ( neighbour->discovery )
 			printf ( " (%s)", neighbour->discovery->name );
 		printf ( "\n" );