diff -r 753b9fbe18be -r 387b9f7cb0ac src/Pure/Tools/build.ML
--- a/src/Pure/Tools/build.ML	Mon Aug 26 21:53:56 2013 +0200
+++ b/src/Pure/Tools/build.ML	Mon Aug 26 21:56:08 2013 +0200
@@ -127,6 +127,8 @@
 
 fun build args_file = Command_Line.tool (fn () =>
     let
+      val _ = SHA1_Samples.test ();
+
       val (command_timings, (do_output, (options, (verbose, (browser_info,
           (parent_name, (chapter, (name, theories)))))))) =
         File.read (Path.explode args_file) |> YXML.parse_body |>