diff --git a/sys/kern/uipc_cow.c b/sys/kern/uipc_cow.c
index 654b6d7095cf..a36f821eebe1 100644
--- a/sys/kern/uipc_cow.c
+++ b/sys/kern/uipc_cow.c
@@ -70,10 +70,10 @@ struct netsend_cow_stats {
 
 static struct netsend_cow_stats socow_stats;
 
-static void socow_iodone(void *addr, void *args);
+static void socow_iodone(struct mbuf *m, void *addr, void *args);
 
 static void
-socow_iodone(void *addr, void *args)
+socow_iodone(struct mbuf *m, void *addr, void *args)
 {	
 	struct sf_buf *sf;
 	vm_page_t pp;