stdErrEnc.Encode(&log.Entry{
				Level:   ErrorKind,
				Message: msg,
				Time:    time.Now().UTC(),
				Trace:   &log.Trace{Message: msg},
			})
		}
		if err := w.rotate(); err != nil {
			msg := fmt.Sprintf("unable to rotate log file %v: %v", w.f.Name(), err)
			stdErrEnc.Encode(&log.Entry{
				Level:   ErrorKind,
				Message: msg,
				Time:    time.Now().UTC(),
				Trace:   &log.Trace{Message: msg},
			})