diff --git a/sys/net/wg/wg_noise.c b/sys/net/wg/wg_noise.c
--- a/sys/net/wg/wg_noise.c
+++ b/sys/net/wg/wg_noise.c
@@ -1204,6 +1204,7 @@
 
 	/* {} */
 	noise_msg_encrypt(en, NULL, 0, key, hs->hs_hash);
+	/* XXX: r_handshake advanced before noise_begin_session may fail (DF-0465) */
 
 	if (noise_begin_session(r)) {
 		getnanouptime(&r->r_last_sent);