[racket] sandbox upset about libcrypto access for comment box

In my on-again, off-again flirtations with the sandbox, I have hit an
error that I don't think I've seen before.

I created a sample student file with a comment box in it. When I try
to load it into a sandbox evaluator, I get the error

file-exists?: `exists' access denied for /usr/lib/racket/libcrypto.so

Removing the comment box makes the error go away. Other than using #|
... |# instead of a comment box (which does make the error go away),
what can I do to tell the sandbox that it's okay to look in the
/usr/lib/racket folder? I'm guessing the answer might have to do with
#:allow-read, but that's the only parameter to make-evaluator and
make-module-evaluator that isn't really documented. :-(

This is with version 5.1.

Thanks,
Todd