Source code get entity escaped after migrating

I have a lot of posts with source code on it. After migrating my blog from wordpress.com to self-hosting, the source code all have HTML entity escaping, for example:

[code]
  printf(quot;helloquot;);
[/code]

This causes the rendered source code become printf(quot;helloquot;) instead of printf("hello")

I think this is because the export/import process was using xml file where all non-suitable characters get escaped.

Is there anyway only normal content get escaped, but not [code] enclosed content when migrating wordpress?