diff --git a/lib/hdb/hdb_err.et b/lib/hdb/hdb_err.et
index 8c6cc0f1c..64f79fc84 100644
--- a/lib/hdb/hdb_err.et
+++ b/lib/hdb/hdb_err.et
@@ -23,5 +23,6 @@ error_code CANT_LOCK_DB,	"Insufficient access to lock database"
 error_code EXISTS,		"Entry already exists in database"
 error_code BADVERSION,		"Wrong database version"
 error_code NO_MKEY,		"No correct master key"
+error_code MANDATORY_OPTION,	"Entry contains unknown mandatory extension"
 
 end