diff -r a873158542d0 -r c1e9c6dfeff8 src/Pure/ML-Systems/multithreading_polyml.ML
--- a/src/Pure/ML-Systems/multithreading_polyml.ML	Wed Sep 22 00:17:35 2010 +0200
+++ b/src/Pure/ML-Systems/multithreading_polyml.ML	Wed Sep 22 00:45:42 2010 +0200
@@ -181,7 +181,7 @@
       let
         val status =
           OS.Process.system ("exec \"$ISABELLE_HOME/lib/scripts/process\" group " ^ pid_name ^
-            " \"exec bash " ^ script_name ^ " > " ^ output_name ^ "\"");
+            " script \"exec bash " ^ script_name ^ " > " ^ output_name ^ "\"");
         val res =
           (case Posix.Process.fromStatus status of
             Posix.Process.W_EXITED => Result 0