diff --git a/includes/tree.h b/includes/tree.h
index 6f375028..30770be6 100644
--- a/includes/tree.h
+++ b/includes/tree.h
@@ -3,7 +3,7 @@
    Definitions for address trees... */
 
 /*
- * Copyright (c) 1996-1999 Internet Software Consortium.
+ * Copyright (c) 1996-2001 Internet Software Consortium.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -47,6 +47,11 @@ typedef struct _pair {
 	struct _pair *cdr;
 } *pair;
 
+struct option_chain_head {
+	int refcnt;
+	pair first;
+};
+
 struct enumeration_value {
 	const char *name;
 	u_int8_t value;