Disable theming for an empty ASPX

I recently added an ASPX page whose sole purpose in life is to redirect in various ways (yes, I could use a handler, no I didn’t in this case). It had no content other than the usual <%@ Page ...%> declaration. No head, body, or html tag. I got the following error message:

Using themed css files requires a header control on the page. (e.g. <head runat="server" />).

So naturally I added <%@ Page EnableTheming="false" ...%>, and … got the same error. Bit of Googling later and found this post from Damien White (which in turn references a Rick Strahl post). End result is that EnableTheming seems a bit useless (at least for this case):

<%@ Page Language="C#" Theme="" ... %>

Setting Theme to nothing works, EnableTheming="false" doesn’t. Bit odd. I know this is old news, but given the trouble I had searching for a solution I thought an extra search result floating around wouldn’t hurt anyone.