Paypal Refund Issue on IPN

Hi All,
I've got a fresh ZC 1.3.5 installed and I've got the Paypal purchasing flow working great with notifications working and all. However, I did a refund on the paypal site today for a test purchase and the debug mails are coming back with an error:

IPN WARNING::Currency/Amount Mismatch. Details: PayPal email address = [email protected]
-> | mc_currency = EUR | submitted_currency = EUR | order_currency = EUR
-> | | mc_gross = -1.00 | converted_amount = 1.00 | order_amount = 1

As you can see, the issue is that there's a mismatch between -1.00 and 1.00. Is PayPal causing this or ZC? Any ideas what I can do to fix it?
As always, many thanks,
Bearaman

I would strongly recommend upgrading to v1.3.6 or if you have not done a lot to the site reinstall with v1.3.6 and then address any issues that you might be having ...

Check your currency settings and make sure you have a default and that the default is marked as 1.00