diff --git a/Tools/msi/msi.py b/Tools/msi/msi.py
index d6a2048..cd67e99 100644
--- a/Tools/msi/msi.py
+++ b/Tools/msi/msi.py
@@ -117,13 +117,13 @@
 
 # Compute the name that Sphinx gives to the docfile
 docfile = ""
-if micro:
-    docfile = str(micro)
+if int(micro):
+    docfile = micro
 if level < 0xf:
     if level == 0xC:
-        docfile = "rc%s" % (serial,)
+        docfile += "rc%s" % (serial,)
     else:
-        docfile = '%x%s' % (level, serial)
+        docfile += '%x%s' % (level, serial)
 docfile = 'python%s%s%s.chm' % (major, minor, docfile)
 
 # Build the mingw import library, libpythonXY.a