diff --git a/bootstrap/Stage7.sml b/bootstrap/Stage7.sml
index 8790040b..ad949085 100644
--- a/bootstrap/Stage7.sml
+++ b/bootstrap/Stage7.sml
@@ -1,61 +1,61 @@
 (*
     Title:      Bootstrap code.
     Author:     David Matthews
     Copyright   David Matthews 2005-2008, 2017, 2020
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License version 2.1 as published by the Free Software Foundation.
     
     This library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.
     
     You should have received a copy of the GNU Lesser General Public
     License along with this library; if not, write to the Free Software
     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *)
 
 (* Build the main basis library. *)
 val () = Bootstrap.use "basis/build.sml";
 
 (* We've now set up the new name space so everything has to be
    compiled into that rather than the old space. *)
     (* XWindows/Motif *)
 val () =
 let
     val xWindowsGeneralCall = RunCall.rtsCallFull1 "PolyXWindowsGeneral"
     val xcall: int*int->int*int = xWindowsGeneralCall
     (* See if the RTS supports the X GetTimeOfDay call. *)
     val isX = (xcall(30, 0); true) handle _ => false
 in
    if isX
    then
    (
         PolyML.make "mlsource/extra/XWindows";
         PolyML.make "mlsource/extra/Motif"
    )
    else ()
 end;
 
 val () = PolyML.print_depth 10;
 
 (* Write out the result as an export file. *)
 local
     val args = CommandLine.arguments();
     (* If we have -o filename use that as the output name.
        N.B.  polyImport takes the first argument that is not recognised as
        an RTS argument and treats that as the file name so any -o must occur
        AFTER the import file. *)
     fun getFile [] = "polyexport" (* Default file name *)
       | getFile ("-o" :: outFile :: _) = outFile
       | getFile (_::tl) = getFile tl
     val fileName = getFile args
 in
     val () = PolyML.shareCommonData PolyML.rootFunction;
     val () = PolyML.export(fileName, PolyML.rootFunction)
 end;
 
 (* And terminate. *)
-OS.Process.exit OS.Process.success;
+OS.Process.exit OS.Process.success : unit;