diff --git a/src/hnbgw_rua.c b/src/hnbgw_rua.c
index 961a5c5..9885553 100644
--- a/src/hnbgw_rua.c
+++ b/src/hnbgw_rua.c
@@ -168,6 +168,11 @@
 	struct hnbgw_context_map *map;
 	int rc;
 
+	if (!cn) {
+		DEBUGP(DRUA, "CN=NULL, discarding message\n");
+		return 0;
+	}
+
 	prim = (struct osmo_scu_prim *) msgb_put(msg, sizeof(*prim));
 	osmo_prim_init(&prim->oph, SCCP_SAP_USER, type, PRIM_OP_REQUEST, msg);