diff --git a/print-null.c b/print-null.c
index 14df5fd..59b691c 100644
--- a/print-null.c
+++ b/print-null.c
@@ -117,7 +117,7 @@
 		break;
 
 	case BSD_AFNUM_ISO:
-		isoclns_print(ndo, p, length, caplen);
+		isoclns_print(ndo, p, length);
 		break;
 
 	case BSD_AFNUM_APPLETALK: