diff --git a/tftp/tftp.go b/tftp/tftp.go
index d958be8..75b7402 100644
--- a/tftp/tftp.go
+++ b/tftp/tftp.go
@@ -71,6 +71,9 @@ type Server struct {
 // calls Serve to handle TFTP requests. If addr is blank, ":69" is
 // used.
 func (s *Server) ListenAndServe(addr string) error {
+	if addr == "" {
+		addr = ":69"
+	}
 	l, err := net.ListenPacket("udp", addr)
 	if err != nil {
 		return err