diff --git a/clatd.h b/clatd.h
index 21f3c95..a42768c 100644
--- a/clatd.h
+++ b/clatd.h
@@ -38,15 +38,13 @@
 
 extern volatile sig_atomic_t running;
 
-void configure_tun_ip(const struct tun_data *tunnel, const char *v4_addr, int mtu);
 void set_capability(uint64_t target_cap);
 void drop_root_and_caps();
 int ipv6_address_changed(const char *interface);
 int configure_clat_ipv6_address(const struct tun_data *tunnel, const char *interface,
                                 const char *src_addr);
-int detect_mtu(const struct in6_addr *plat_subnet, uint32_t plat_suffix, uint32_t mark);
-void configure_interface(const char *uplink_interface, const char *plat_prefix, const char *v4_addr,
-                         const char *v6, struct tun_data *tunnel, uint32_t mark);
+void configure_interface(const char *uplink_interface, const char *plat_prefix, const char *v6,
+                         struct tun_data *tunnel);
 void event_loop(struct tun_data *tunnel);
 
 /* function: parse_int