src/Pure/Concurrent/lazy.ML

--- a/src/Pure/Concurrent/lazy.ML	Fri Aug 19 13:55:32 2011 +0200
+++ b/src/Pure/Concurrent/lazy.ML	Fri Aug 19 14:01:20 2011 +0200
@@ -57,7 +57,7 @@
           val (expr, x) =
             Synchronized.change_result var
               (fn Expr e =>
-                    let val x = Future.promise ()
+                    let val x = Future.promise I
                     in ((SOME e, x), Result x) end
                 | Result x => ((NONE, x), Result x));
         in