diff --git a/include/osmocom/ranap/ranap_common.h b/include/osmocom/ranap/ranap_common.h
index 229d134..b7682e5 100644
--- a/include/osmocom/ranap/ranap_common.h
+++ b/include/osmocom/ranap/ranap_common.h
@@ -634,3 +634,4 @@
 void ranap_set_log_area(int log_area);
 
 int ranap_parse_lai(struct gprs_ra_id *ra_id, const RANAP_LAI_t *lai);
+int ranap_ip_from_transp_layer_addr(const BIT_STRING_t *in, uint32_t *ip);