diff --git a/frontend/json/jsonparse.h b/frontend/json/jsonparse.h
index 6b444be9..12bf6dcd 100644
--- a/frontend/json/jsonparse.h
+++ b/frontend/json/jsonparse.h
@@ -24,6 +24,6 @@
 #include <istream>
 #include "design.h"
 
-extern	void	parse_json_file(std::istream *&, std::string , Design *);
+extern	void	parse_json_file(std::istream *&, std::string &, Design *);
 
 #endif