diff --git a/src/hlr_ussd.c b/src/hlr_ussd.c
index 4024780..773c571 100644
--- a/src/hlr_ussd.c
+++ b/src/hlr_ussd.c
@@ -336,11 +336,11 @@
 		ss_tx_ussd_7bit(ss, true, req->invoke_id, buf);
 		break;
 	case -ENOENT:
-		ss_tx_error(ss, true, GSM0480_ERR_CODE_UNKNOWN_SUBSCRIBER);
+		ss_tx_error(ss, req->invoke_id, GSM0480_ERR_CODE_UNKNOWN_SUBSCRIBER);
 		break;
 	case -EIO:
 	default:
-		ss_tx_error(ss, true, GSM0480_ERR_CODE_SYSTEM_FAILURE);
+		ss_tx_error(ss, req->invoke_id, GSM0480_ERR_CODE_SYSTEM_FAILURE);
 		break;
 	}
 	return 0;