diff --git a/msg.go b/msg.go
index 31d0fa33..34896a75 100644
--- a/msg.go
+++ b/msg.go
@@ -921,7 +921,7 @@ func packStructValue(val reflect.Value, msg []byte, off int, compression map[str
 				copy(msg[off:off+len(s)], s)
 				off += len(s)
 			case `dns:"octet"`:
-				bytesTmp := make([]byte, 256*4+1)
+				bytesTmp := make([]byte, 256)
 				off, err = packOctetString(fv.String(), msg, off, bytesTmp)
 				if err != nil {
 					return lenmsg, err