RFC 6608 specifies subcode 0 to be value "Unspecified Error"
diff --git a/print-bgp.c b/print-bgp.c
index f77bba8..4cbc191 100644
--- a/print-bgp.c
+++ b/print-bgp.c
@@ -308,6 +308,7 @@
 };
 
 static const struct tok bgp_notify_minor_fsm_values[] = {
+    { 0,                        "Unspecified Error"},
     { 1,                        "In OpenSent State"},
     { 2,                        "In OpenConfirm State"},
     { 3,                        "In Established State"},