diff --git a/src/cam/options.h b/src/cam/options.h
index f02eeca2..d0defb4b 100644
--- a/src/cam/options.h
+++ b/src/cam/options.h
@@ -79,9 +79,11 @@ public:
 		       OptionArgument argument = ArgumentNone);
 
 	virtual Options parse(const char *arguments);
-	void usage(int indent);
 
 private:
+	friend class OptionsParser;
+	void usage(int indent);
+
 	std::map<std::string, Option> optionsMap_;
 };