diff --git a/ospf6d/ospf6_network.h b/ospf6d/ospf6_network.h
index 9a4d795..fd8758e 100644
--- a/ospf6d/ospf6_network.h
+++ b/ospf6d/ospf6_network.h
@@ -29,22 +29,22 @@
 extern struct in6_addr alldrouters6;
 
 /* Function Prototypes */
-void ospf6_set_reuseaddr ();
-void ospf6_reset_mcastloop ();
-void ospf6_set_pktinfo ();
-void ospf6_set_checksum ();
+extern void ospf6_set_reuseaddr (void);
+extern void ospf6_reset_mcastloop (void);
+extern void ospf6_set_pktinfo (void);
+extern void ospf6_set_checksum (void);
 
-int ospf6_serv_sock ();
+extern int ospf6_serv_sock (void);
 
-void ospf6_join_allspfrouters (u_int);
-void ospf6_leave_allspfrouters (u_int);
-void ospf6_join_alldrouters (u_int);
-void ospf6_leave_alldrouters (u_int);
+extern void ospf6_join_allspfrouters (u_int);
+extern void ospf6_leave_allspfrouters (u_int);
+extern void ospf6_join_alldrouters (u_int);
+extern void ospf6_leave_alldrouters (u_int);
 
-int ospf6_sendmsg (struct in6_addr *, struct in6_addr *,
-                   unsigned int *, struct iovec *);
-int ospf6_recvmsg (struct in6_addr *, struct in6_addr *,
-                   unsigned int *, struct iovec *);
+extern int ospf6_sendmsg (struct in6_addr *, struct in6_addr *,
+                          unsigned int *, struct iovec *);
+extern int ospf6_recvmsg (struct in6_addr *, struct in6_addr *,
+                          unsigned int *, struct iovec *);
 
 #endif /* OSPF6_NETWORK_H */