diff --git a/NPLib/Core/NPOptionManager.cxx b/NPLib/Core/NPOptionManager.cxx
index 01f9cb8c1b17621f0d5d8ac783b0e6ce3c3b426b..79f648d3175074a53a7ef494a4d04585c7f03c41 100644
--- a/NPLib/Core/NPOptionManager.cxx
+++ b/NPLib/Core/NPOptionManager.cxx
@@ -422,7 +422,7 @@ void NPOptionManager::DisplayHelp(){
   std::cout << std::endl << "NPSimulation only:"<<std::endl;
   std::cout << "\t-M <arg>\t\t\tExecute Geant4 macro <arg> at startup" << std::endl ;
   std::cout << "\t-B <arg>\t\t\tExecute in batch mode (no ui) with Geant4 macro <arg> at startup" << std::endl ;
-
+  std::cout << "\t--random-seed <arg>\t\tSet the random generator seed to <arg> (unsigned int)" << std::endl ;
   std::cout << std::endl << std::endl ;
 
   // exit current program