curlyfry, that sounds like market timing. Keep emotions out of investing.
martin, welcome to being an international investor. That's what the rest of the world is experiencing and exposed to the moment they invest in indexes calculated in dollars, or directly in American stocks.
There are ways to hedge against currency fluctuations, end even funds which have this kind of hedge included. Usually, this adds complexity and additional cost.
So what exactly are you afraid of? Losing a little performance, or losing a lot? It could even go the other way... you could win.
In the end, the usual advice is keep things simple, ride out the waves of up and down, nobody can predict the future and in the long run the market always goes up. If you have enough time currency exchange ratios don't matter much. Control your risk with a sound asset allocation.