diff --git a/IPython/upgrade_dir.py b/IPython/upgrade_dir.py
index 4eda389..aa9ed9c 100644
--- a/IPython/upgrade_dir.py
+++ b/IPython/upgrade_dir.py
@@ -36,7 +36,7 @@ def upgrade_dir(srcdir, tgtdir):
 
     def pr(s):
         print s
-    junk = ['.svn','ipythonrc*','*.pyc', '*~', '.hg']
+    junk = ['.svn','ipythonrc*','*.pyc', '*.pyo', '*~', '.hg']
     
     def ignorable(p):
         for pat in junk: