diff --git a/openbsc/src/bsc/osmo_bsc_filter.c b/openbsc/src/bsc/osmo_bsc_filter.c
index e222ac9..d2735a6 100644
--- a/openbsc/src/bsc/osmo_bsc_filter.c
+++ b/openbsc/src/bsc/osmo_bsc_filter.c
@@ -83,6 +83,9 @@
 	case GSM_MI_TYPE_IMSI:
 		subscr = subscr_active_by_imsi(conn->bts->network, mi_string);
 		break;
+	default:
+		subscr = NULL;
+		break;
 	}
 
 	if (!subscr) {