diff --git a/src/gb/gprs_bssgp.c b/src/gb/gprs_bssgp.c
index 5ef1887..b8c6c74 100644
--- a/src/gb/gprs_bssgp.c
+++ b/src/gb/gprs_bssgp.c
@@ -998,7 +998,7 @@
 		LOGP(DBSSGP, LOGL_NOTICE, "NSEI=%u/BVCI=%u Rejecting PDU "
 			"type %u for unknown BVCI\n", msgb_nsei(msg), ns_bvci,
 			pdu_type);
-		return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI, NULL, msg);
+		return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI, &ns_bvci, msg);
 	}
 
 	if (bctx) {
diff --git a/src/gb/gprs_bssgp_util.c b/src/gb/gprs_bssgp_util.c
index ae4647e..261e0b0 100644
--- a/src/gb/gprs_bssgp_util.c
+++ b/src/gb/gprs_bssgp_util.c
@@ -99,6 +99,20 @@
 	struct bssgp_normal_hdr *bgph =
 			(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));
 
+	/* GSM 08.18, 10.4.14.1: The BVCI must be included if (and only if) the
+	   cause is either "BVCI blocked" or "BVCI unknown" */
+	if (cause == BSSGP_CAUSE_UNKNOWN_BVCI || cause == BSSGP_CAUSE_BVCI_BLOCKED) {
+		if (bvci == NULL)
+			LOGP(DBSSGP, LOGL_ERROR, "BSSGP Tx STATUS, cause=%s: "
+			     "missing conditional BVCI\n",
+			     bssgp_cause_str(cause));
+	} else {
+		if (bvci != NULL)
+			LOGP(DBSSGP, LOGL_ERROR, "BSSGP Tx STATUS, cause=%s: "
+			     "unexpected conditional BVCI\n",
+			     bssgp_cause_str(cause));
+	}
+
 	LOGP(DBSSGP, LOGL_NOTICE, "BSSGP BVCI=%u Tx STATUS, cause=%s\n",
 		bvci ? *bvci : 0, bssgp_cause_str(cause));
 	msgb_nsei(msg) = msgb_nsei(orig_msg);