Index: sys/netpfil/pf/pf.c
===================================================================
--- sys/netpfil/pf/pf.c
+++ sys/netpfil/pf/pf.c
@@ -4076,7 +4076,9 @@
 			dnflow.f_id.dst_ip6 = dst->v6;
 			break;
 		default:
-			panic("Unknown address family");
+			if (af > AF_MAX) {
+				panic("Unknown address family %d", af);
+			} 
 		}
 
 		mtag->flags |= PF_TAG_DUMMYNET;