diff --git a/src/Pure/General/mailman.scala b/src/Pure/General/mailman.scala
--- a/src/Pure/General/mailman.scala
+++ b/src/Pure/General/mailman.scala
@@ -1,73 +1,71 @@
 /*  Title:      Pure/General/mailman.scala
     Author:     Makarius
 
 Support for Mailman list servers.
 */
 
 package isabelle
 
 
 import java.net.URL
 
 
 object Mailman
 {
   /* mailing list archives */
 
   def archive(url: URL, name: String = ""): Archive =
   {
     val text = Url.read(url)
     val hrefs = """href="([^"]+\.txt(?:\.gz)?)"""".r.findAllMatchIn(text).map(_.group(1)).toList
     val title =
       """<title>The ([^</>]*) Archives</title>""".r.findFirstMatchIn(text).map(_.group(1))
     val list_url =
       Url(Library.take_suffix[Char](_ == '/', Url.trim_index(url).toString.toList)._1.mkString + "/")
     val list_name =
       (proper_string(name) orElse title).getOrElse(error("Failed to determine mailing list name"))
     new Archive(list_url, list_name, hrefs)
   }
 
   class Archive private[Mailman](val list_url: URL, val list_name: String, hrefs: List[String])
   {
     override def toString: String = list_name
 
-    def download(
-      target_dir: Path = Path.current,
-      progress: Progress = new Progress): List[Path] =
+    def download(target_dir: Path, progress: Progress = new Progress): List[Path] =
     {
       val dir = target_dir + Path.basic(list_name)
       Isabelle_System.make_directory(dir)
 
       hrefs.flatMap(name =>
         {
           val path = dir + Path.basic(name)
           val url = new URL(list_url, name)
           val connection = url.openConnection
           try {
             val length = connection.getContentLengthLong
             val timestamp = connection.getLastModified
             val file = path.file
             if (file.isFile && file.length == length && file.lastModified == timestamp) None
             else {
               progress.echo("Getting " + url)
               val bytes =
                 using(connection.getInputStream)(Bytes.read_stream(_, hint = length.toInt max 1024))
               Bytes.write(file, bytes)
               file.setLastModified(timestamp)
               Some(path)
             }
           }
           finally { connection.getInputStream.close }
         })
     }
   }
 
 
   /* Isabelle mailing lists */
 
   def isabelle_users: Archive =
     archive(Url("https://lists.cam.ac.uk/pipermail/cl-isabelle-users"), name = "isabelle-users")
 
   def isabelle_dev: Archive =
     archive(Url("https://mailmanbroy.informatik.tu-muenchen.de/pipermail/isabelle-dev"))
 }