diff --git a/bgpd/bgp_aspath.h b/bgpd/bgp_aspath.h
index d8b41fa..2b4625c 100644
--- a/bgpd/bgp_aspath.h
+++ b/bgpd/bgp_aspath.h
@@ -72,8 +72,8 @@
 extern struct aspath *aspath_filter_exclude (struct aspath *, struct aspath *);
 extern struct aspath *aspath_add_seq (struct aspath *, as_t);
 extern struct aspath *aspath_add_confed_seq (struct aspath *, as_t);
-extern int aspath_cmp_left (struct aspath *, struct aspath *);
-extern int aspath_cmp_left_confed (struct aspath *, struct aspath *);
+extern int aspath_cmp_left (const struct aspath *, const struct aspath *);
+extern int aspath_cmp_left_confed (const struct aspath *, const struct aspath *);
 extern struct aspath *aspath_delete_confed_seq (struct aspath *);
 extern struct aspath *aspath_empty (void);
 extern struct aspath *aspath_empty_get (void);