diff --git a/openbsc/src/bsc/osmo_bsc_filter.c b/openbsc/src/bsc/osmo_bsc_filter.c
index 7052cfe..965b7c5 100644
--- a/openbsc/src/bsc/osmo_bsc_filter.c
+++ b/openbsc/src/bsc/osmo_bsc_filter.c
@@ -66,3 +66,11 @@
 
 	return 0;
 }
+
+/**
+ * Messages coming back from the MSC.
+ */
+int bsc_scan_msc_msg(struct gsm_subscriber_connection *conn, struct msgb *msg)
+{
+	return 0;
+}