diff --git a/ospf6d/ospf6d.h b/ospf6d/ospf6d.h
index 2d1f725..b6f1b73 100644
--- a/ospf6d/ospf6d.h
+++ b/ospf6d/ospf6d.h
@@ -112,10 +112,10 @@
 
 
 /* Function Prototypes */
-struct route_node *route_prev (struct route_node *node);
+extern struct route_node *route_prev (struct route_node *node);
 
-void ospf6_debug ();
-void ospf6_init ();
+extern void ospf6_debug (void);
+extern void ospf6_init (void);
 
 #endif /* OSPF6D_H */