diff --git a/sys/netpfil/ipfilter/netinet/fil.c b/sys/netpfil/ipfilter/netinet/fil.c
--- a/sys/netpfil/ipfilter/netinet/fil.c
+++ b/sys/netpfil/ipfilter/netinet/fil.c
@@ -3922,7 +3922,9 @@
 		for (i = 0; i < FR_NUM(fr->fr_ifas); i++) {
 			if ((ifp != NULL) && (fr->fr_ifas[i] != ifp))
 				continue;
-			if (fr->fr_ifnames[i] == -1)
+			if (fr->fr_ifnames[i] < 0)
+				continue;
+			if (strlen(fr->fr_ifnames[i]) > fr->fr_namelen)
 				continue;
 			name = FR_NAME(fr, fr_ifnames[i]);
 			fr->fr_ifas[i] = ipf_resolvenic(softc, name, v);