Generate the product code properly
diff --git a/Tools/msi/msilib.py b/Tools/msi/msilib.py
index 5f8ef28..61715fc 100644
--- a/Tools/msi/msilib.py
+++ b/Tools/msi/msilib.py
@@ -315,7 +315,7 @@
         si.SetProperty(PID_TEMPLATE, "Intel64;1033")
     else:
         si.SetProperty(PID_TEMPLATE, "Intel;1033")
-    si.SetProperty(PID_REVNUMBER, ProductCode) # XXX should be package code
+    si.SetProperty(PID_REVNUMBER, gen_uuid())
     si.SetProperty(PID_WORDCOUNT, 2) # long file names, compressed, original media
     si.SetProperty(PID_PAGECOUNT, 200)
     si.SetProperty(PID_APPNAME, "Python MSI Library")