1 files changed, 1 insertions, 1 deletions
diff --git a/src/parser.h b/src/parser.h
index e46fc719..25c4a7e3 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -118,7 +118,7 @@ public:
 
   ptr_op_t parse(std::istream&           in,
                  const parse_flags_t&    flags           = PARSE_DEFAULT,
-                 const optional<string>& original_string = NULL);
+                 const optional<string>& original_string = boost::none);
 };
 
 } // namespace ledger