diff --git a/sys/src/cmd/ip/torrent.c b/sys/src/cmd/ip/torrent.c
index 54d631e03..9f37a1f4e 100644
--- a/sys/src/cmd/ip/torrent.c
+++ b/sys/src/cmd/ip/torrent.c
@@ -295,7 +295,7 @@ unpack(uchar *s, int n, char *fmt, ...)
 			s += 4;
 			break;
 		case 'v':
-			if(s+4 > e) goto Err;
+			if(s+8 > e) goto Err;
 			*va_arg(arg, vlong*) = 
 				(vlong)s[0]<<56 | 
 				(vlong)s[1]<<48 |