diff --git a/openbsc/include/openbsc/bsc_nat.h b/openbsc/include/openbsc/bsc_nat.h
index 61df389..b3a12f5 100644
--- a/openbsc/include/openbsc/bsc_nat.h
+++ b/openbsc/include/openbsc/bsc_nat.h
@@ -258,6 +258,11 @@
 struct bsc_connection *bsc_nat_find_bsc(struct bsc_nat *nat, struct msgb *msg, int *_lac);
 
 /**
+ * Content filtering.
+ */
+int bsc_nat_filter_sccp_cr(struct bsc_connection *, struct msgb *msg, struct bsc_nat_parsed *);
+
+/**
  * SCCP patching and handling
  */
 int create_sccp_src_ref(struct bsc_connection *bsc, struct msgb *msg, struct bsc_nat_parsed *parsed);