diff -r f6a2e5ce2ce5 -r 5f5649ac8235 src/Pure/Isar/outer_syntax.ML
--- a/src/Pure/Isar/outer_syntax.ML	Sun Aug 21 20:25:49 2011 +0200
+++ b/src/Pure/Isar/outer_syntax.ML	Sun Aug 21 20:42:26 2011 +0200
@@ -62,7 +62,9 @@
 local
 
 fun terminate false = Scan.succeed ()
-  | terminate true = Parse.group "end of input" (Scan.option Parse.sync -- Parse.semicolon >> K ());
+  | terminate true =
+      Parse.group (fn () => "end of input")
+        (Scan.option Parse.sync -- Parse.semicolon >> K ());
 
 fun body cmd (name, _) =
   (case cmd name of