diff --git a/parse.h b/parse.h
index c5a7417..f2265a4 100644
--- a/parse.h
+++ b/parse.h
@@ -29,6 +29,7 @@
 	unsigned int oval;		/* output value */
 	const char *help;		/* help text for sub option */
 	int or;				/* OR value */
+	void *cb;			/* sub-option callback */
 };
 
 #define OPT_LEN_MAX 	4096