diff --git a/generator/feature_builder.hpp b/generator/feature_builder.hpp
index ec23313ccf..3720de4c59 100644
--- a/generator/feature_builder.hpp
+++ b/generator/feature_builder.hpp
@@ -261,7 +261,7 @@ namespace feature
 
   /// Process features in .dat file.
   template <class ToDo>
-  void ForEachFromDatRawFormat(string const & fName, ToDo & toDo)
+  void ForEachFromDatRawFormat(string const & fName, ToDo && toDo)
   {
     FileReader reader(fName);
     ReaderSource<FileReader> src(reader);