--- a/src/Pure/System/components.scala	Sat Dec 08 14:28:14 2018 +0100
+++ b/src/Pure/System/components.scala	Sat Dec 08 14:58:56 2018 +0100
@@ -36,8 +36,7 @@
   {
     val name = Archive.get_name(archive.file_name)
     progress.echo("Unpacking " + name)
-    Isabelle_System.gnutar(
-      "-C " + File.bash_path(dir) + " -xzf " + File.bash_path(archive.absolute)).check
+    Isabelle_System.gnutar("-xzf " + File.bash_path(archive), dir = dir).check
     name
   }