diff --git a/ripd/ripd.c b/ripd/ripd.c
index 2e2b284..ec7bd19 100644
--- a/ripd/ripd.c
+++ b/ripd/ripd.c
@@ -1131,8 +1131,8 @@
 
   /* The datagram's IPv4 source address should be checked to see
      whether the datagram is from a valid neighbor; the source of the
-     datagram must be on a directly connected network  */
-  if (! if_valid_neighbor (from->sin_addr)) 
+     datagram must be on a directly connected network (RFC2453 - Sec. 3.9.2) */
+  if (if_lookup_address(from->sin_addr) == NULL) 
     {
       zlog_info ("This datagram doesn't came from a valid neighbor: %s",
 		 inet_ntoa (from->sin_addr));