diff --git a/sls/trunk/src/option.cc b/sls/trunk/src/option.cc
index e61e9905ede0c055edff09f8ff54959dc475d7d3..f56cba96a258b0ddebaa59baaf82d158c99f35ca 100644
--- a/sls/trunk/src/option.cc
+++ b/sls/trunk/src/option.cc
@@ -41,7 +41,7 @@ Option::Option() {
 */
 void Option::usage(const char *name, ostream &out) const {
   out << "usage: " << name
-      << " [-h|--help] [-d|--database file] [-v|--verbose] [-p port]" << std::endl
+      << " [-h|--help] [-d|--database file] [-v|--verbose] [-p port] [-t max-thread]" << std::endl
       << "-h | --help           : Print this help." << std::endl
       << "-d | --database file  : Define database (def: /var/db/sls.db)." << std::endl
       << "-v | --verbose        : Set verbose mode." << std::endl