diff -r 6019cfb8256c -r bbcb75c58086 src/Pure/System/options.scala
--- a/src/Pure/System/options.scala	Sat Sep 16 15:35:56 2017 +0200
+++ b/src/Pure/System/options.scala	Sat Sep 16 16:19:34 2017 +0200
@@ -147,7 +147,7 @@
 
   /* Isabelle tool wrapper */
 
-  val isabelle_tool = Isabelle_Tool("option", "print Isabelle system options", args =>
+  val isabelle_tool = Isabelle_Tool("options", "print Isabelle system options", args =>
   {
     var build_options = false
     var get_option = ""