diff --git a/include/just_gtfs/just_gtfs.h b/include/just_gtfs/just_gtfs.h
index d8635a6..0470928 100644
--- a/include/just_gtfs/just_gtfs.h
+++ b/include/just_gtfs/just_gtfs.h
@@ -1348,6 +1348,7 @@ private:
   inline void write_translations(std::ofstream & out) const;
   inline void write_attributions(std::ofstream & out) const;
 
+protected:
   std::string gtfs_directory;
 
   Agencies agencies;