diff --git a/openbsc/src/libmsc/gsm_04_11.c b/openbsc/src/libmsc/gsm_04_11.c
index 3a2effe..48a87e0 100644
--- a/openbsc/src/libmsc/gsm_04_11.c
+++ b/openbsc/src/libmsc/gsm_04_11.c
@@ -873,7 +873,7 @@
 	struct msgb *msg = gsm411_msgb_alloc();
 	struct gsm_trans *trans;
 	uint8_t *data, *rp_ud_len;
-	uint8_t msg_ref = sms_next_rp_msg_ref(conn);
+	uint8_t msg_ref = sms_next_rp_msg_ref(&conn->next_rp_ref);
 	int transaction_id;
 	int rc;