libpq: compatibility with server versions

Hi all,

I am using libpq 8.2.4 (and my own wrapper around it) for a
long time now. Due to some performance penalties I would
like to upgrade to 8.4.x libpq.

Is it o.k. if I upgraded my libpq to the newer 8.4
libraries but would still connect to old 8.2 servers?

Are there any compatibility issues to be aware of?

(I am not talking about upgrading the server nor the steps
to take for upgrading the data itself.)

Thank You
 Felix