diff --git a/ospf6d/ospf6_area.h b/ospf6d/ospf6_area.h
index c7c5ee3..e8a4fbd 100644
--- a/ospf6d/ospf6_area.h
+++ b/ospf6d/ospf6_area.h
@@ -57,6 +57,7 @@
 
   struct thread  *thread_spf_calculation;
   struct thread  *thread_route_calculation;
+  u_int32_t spf_calculation;	/* SPF calculation count */
 
   struct thread *thread_router_lsa;
   struct thread *thread_intra_prefix_lsa;