diff -r b93cc7d73431 -r 38c89353b349 src/Pure/Tools/doc.scala
--- a/src/Pure/Tools/doc.scala	Sun Feb 28 17:37:20 2016 +0100
+++ b/src/Pure/Tools/doc.scala	Sun Feb 28 17:40:01 2016 +0100
@@ -96,7 +96,7 @@
   def main(args: Array[String])
   {
     Command_Line.tool0 {
-      val getopts = Getopts(() => """
+      val getopts = Getopts("""
 Usage: isabelle doc [DOC ...]
 
   View Isabelle documentation.