diff --git a/ospfd/ospf_network.h b/ospfd/ospf_network.h
index 52a25fd..1b43df1 100644
--- a/ospfd/ospf_network.h
+++ b/ospfd/ospf_network.h
@@ -24,11 +24,15 @@
 #define _ZEBRA_OSPF_NETWORK_H
 
 /* Prototypes. */
-int ospf_if_add_allspfrouters (struct ospf *, struct prefix *, unsigned int);
-int ospf_if_drop_allspfrouters (struct ospf *, struct prefix *, unsigned int);
-int ospf_if_add_alldrouters (struct ospf *, struct prefix *, unsigned int);
-int ospf_if_drop_alldrouters (struct ospf *, struct prefix *, unsigned int);
-int ospf_if_ipmulticast (struct ospf *, struct prefix *, unsigned int);
-int ospf_sock_init (void);
+extern int ospf_if_add_allspfrouters (struct ospf *, struct prefix *,
+				      unsigned int);
+extern int ospf_if_drop_allspfrouters (struct ospf *, struct prefix *,
+				       unsigned int);
+extern int ospf_if_add_alldrouters (struct ospf *, struct prefix *,
+				    unsigned int);
+extern int ospf_if_drop_alldrouters (struct ospf *, struct prefix *,
+				     unsigned int);
+extern int ospf_if_ipmulticast (struct ospf *, struct prefix *, unsigned int);
+extern int ospf_sock_init (void);
 
 #endif /* _ZEBRA_OSPF_NETWORK_H */