--- a/src/Pure/General/xml.scala Thu Jun 23 14:48:32 2011 +0200
+++ b/src/Pure/General/xml.scala Thu Jun 23 14:52:32 2011 +0200
@@ -6,6 +6,7 @@
package isabelle
+import java.lang.System
import java.util.WeakHashMap
import java.lang.ref.WeakReference
import javax.xml.parsers.DocumentBuilderFactory