Asian characters in JFreeChart get rendered as squares in IE 8 but not in Firefox

Question

I'm generating a chart that contains Asian characters. The characters render fine in Firefox, but not in IE 8. If I debug in Eclipse, I can see that the characters are fine in both cases before getting rendered, so they're not getting screwed up before the server or by the server. The Content-Type of the server response header is the following in both cases:

application/xml;charset=UTF-8

The meta tag of the HTML document also specifies UTF-8 as the charset.

The images are rendered in PNG format. Why do the characters get rendered as squares in IE 8 and what can I do about it?