diff -r 2e3346fc880f Lib/zipfile.py
--- a/Lib/zipfile.py	Mon May 02 12:31:17 2011 -0400
+++ b/Lib/zipfile.py	Mon May 02 18:50:32 2011 +0200
@@ -1179,7 +1179,6 @@
             zinfo.compress_size = len(data)    # Compressed size
         else:
             zinfo.compress_size = zinfo.file_size
-        zinfo.header_offset = self.fp.tell()    # Start of header data
         self.fp.write(zinfo.FileHeader())
         self.fp.write(data)
         self.fp.flush()