diff --git a/bgpd/bgp_attr.c b/bgpd/bgp_attr.c
index 5c3d153..cda522a 100644
--- a/bgpd/bgp_attr.c
+++ b/bgpd/bgp_attr.c
@@ -773,7 +773,7 @@
      with the Attribute Type Code, then the Error Subcode is set to
      Attribute Flags Error.  The Data field contains the erroneous
      attribute (type, length and value). */
-  if (flag != BGP_ATTR_FLAG_TRANS)
+  if ((flag & ~BGP_ATTR_FLAG_EXTLEN) != BGP_ATTR_FLAG_TRANS)
   {
     if (CHECK_FLAG (flag, BGP_ATTR_FLAG_OPTIONAL))
       zlog (peer->log, LOG_ERR, "ORIGIN attribute must not be flagged as \"optional\" (%u)", flag);
@@ -980,7 +980,7 @@
   total = length + (CHECK_FLAG (flag, BGP_ATTR_FLAG_EXTLEN) ? 4 : 3);
 
   /* Flags check. */
-  if (flag != BGP_ATTR_FLAG_TRANS)
+  if ((flag & ~BGP_ATTR_FLAG_EXTLEN) != BGP_ATTR_FLAG_TRANS)
   {
     if (CHECK_FLAG (flag, BGP_ATTR_FLAG_OPTIONAL))
       zlog (peer->log, LOG_ERR, "NEXT_HOP attribute must not be flagged as \"optional\" (%u)", flag);
@@ -1035,7 +1035,7 @@
   total = length + (CHECK_FLAG (flag, BGP_ATTR_FLAG_EXTLEN) ? 4 : 3);
 
   /* Flag checks. */
-  if (flag != BGP_ATTR_FLAG_OPTIONAL)
+  if ((flag & ~BGP_ATTR_FLAG_EXTLEN) != BGP_ATTR_FLAG_OPTIONAL)
   {
     if (! CHECK_FLAG (flag, BGP_ATTR_FLAG_OPTIONAL))
       zlog (peer->log, LOG_ERR, "MULTI_EXIT_DISC attribute must be flagged as \"optional\" (%u)", flag);
@@ -1074,7 +1074,7 @@
 
   total = length + (CHECK_FLAG (flag, BGP_ATTR_FLAG_EXTLEN) ? 4 : 3);
   /* Flag checks. */
-  if (flag != BGP_ATTR_FLAG_TRANS)
+  if ((flag & ~BGP_ATTR_FLAG_EXTLEN) != BGP_ATTR_FLAG_TRANS)
   {
     if (CHECK_FLAG (flag, BGP_ATTR_FLAG_OPTIONAL))
       zlog (peer->log, LOG_ERR, "LOCAL_PREF attribute must not be flagged as \"optional\" (%u)", flag);
@@ -1122,7 +1122,7 @@
 
   total = length + (CHECK_FLAG (flag, BGP_ATTR_FLAG_EXTLEN) ? 4 : 3);
   /* Flag checks. */
-  if (flag != BGP_ATTR_FLAG_TRANS)
+  if ((flag & ~BGP_ATTR_FLAG_EXTLEN) != BGP_ATTR_FLAG_TRANS)
   {
     if (CHECK_FLAG (flag, BGP_ATTR_FLAG_OPTIONAL))
       zlog (peer->log, LOG_ERR, "ATOMIC_AGGREGATE attribute must not be flagged as \"optional\" (%u)", flag);