diff --git a/isisd/isis_dynhn.h b/isisd/isis_dynhn.h
index 379c454..f06a067 100644
--- a/isisd/isis_dynhn.h
+++ b/isisd/isis_dynhn.h
@@ -32,9 +32,9 @@
 };
 
 void dyn_cache_init (void);
-void isis_dynhn_insert (u_char * id, struct hostname *hostname, int level);
-void isis_dynhn_remove (u_char * id);
-struct isis_dynhn *dynhn_find_by_id (u_char * id);
+void isis_dynhn_insert (const u_char * id, struct hostname *hostname, int level);
+void isis_dynhn_remove (const u_char * id);
+struct isis_dynhn *dynhn_find_by_id (const u_char * id);
 struct isis_dynhn *dynhn_find_by_name (const char *hostname);
 void dynhn_print_all (struct vty *vty);