diff --git a/ospfd/ospf_lsa.c b/ospfd/ospf_lsa.c
index 493209a..5579d8e 100644
--- a/ospfd/ospf_lsa.c
+++ b/ospfd/ospf_lsa.c
@@ -192,6 +192,18 @@
   return fletcher_checksum(buffer, len, checksum_offset);
 }
 
+int
+ospf_lsa_checksum_valid (struct lsa_header *lsa)
+{
+  u_char *buffer = (u_char *) &lsa->options;
+  int options_offset = buffer - (u_char *) &lsa->ls_age; /* should be 2 */
+
+  /* Skip the AGE field */
+  u_int16_t len = ntohs(lsa->length) - options_offset;
+
+  return(fletcher_checksum(buffer, len, FLETCHER_CHECKSUM_VALIDATE) == 0);
+}
+
 
 
 /* Create OSPF LSA. */
diff --git a/ospfd/ospf_packet.c b/ospfd/ospf_packet.c
index 351fb21..ede5908 100644
--- a/ospfd/ospf_packet.c
+++ b/ospfd/ospf_packet.c
@@ -1590,7 +1590,7 @@
 
       /* Validate the LSA's LS checksum. */
       sum = lsah->checksum;
-      if (sum != ospf_lsa_checksum (lsah))
+      if (! ospf_lsa_checksum_valid (lsah))
 	{
 	  /* (bug #685) more details in a one-line message make it possible
 	   * to identify problem source on the one hand and to have a better