diff --git a/Tools/msi/msi.py b/Tools/msi/msi.py
index bf9ef87..c5e630b 100644
--- a/Tools/msi/msi.py
+++ b/Tools/msi/msi.py
@@ -398,7 +398,7 @@
               ("VerdanaRed9", "Verdana", 9, 255, 0),
              ])
 
-    compileargs = r'-Wi "[TARGETDIR]Lib\compileall.py" -f -x "bad_coding|badsyntax|site-packages|py3_" "[TARGETDIR]Lib"'
+    compileargs = r'-Wi "[TARGETDIR]Lib\compileall.py" -f -x "bad_coding|badsyntax|site-packages|py3_|py2_test_grammar" "[TARGETDIR]Lib"'
     lib2to3args = r'-c "import lib2to3.pygram, lib2to3.patcomp;lib2to3.patcomp.PatternCompiler()"'
     # See "CustomAction Table"
     add_data(db, "CustomAction", [