diff --git a/zebra/ChangeLog b/zebra/ChangeLog
index cbfb4b6..6c921fd 100644
--- a/zebra/ChangeLog
+++ b/zebra/ChangeLog
@@ -1,3 +1,8 @@
+2005-09-24 Hasso Tepper <hasso at quagga.net>
+
+	* rib.h: Add note about behaviour of rib_add_ipv[46]* functions -
+	  add is treated as implicit withdraw.
+
 2005-09-21 David Young <dyoung@ojctech.com>
 
 	* zebra_rib.c: Reduce the height of some staircases. Fix
diff --git a/zebra/rib.h b/zebra/rib.h
index 12ed8b7..8d12846 100644
--- a/zebra/rib.h
+++ b/zebra/rib.h
@@ -213,6 +213,9 @@
 extern struct route_table *vrf_table (afi_t afi, safi_t safi, u_int32_t id);
 extern struct route_table *vrf_static_table (afi_t afi, safi_t safi, u_int32_t id);
 
+/* NOTE:
+ * All rib_add_ipv[46]* functions will not just add prefix into RIB, but
+ * also implicitly withdraw equal prefix of same type. */
 extern int rib_add_ipv4 (int type, int flags, struct prefix_ipv4 *p, 
 			 struct in_addr *gate, unsigned int ifindex, 
 			 u_int32_t vrf_id, u_int32_t, u_char);