Cannot make expense refund because the vendor's currency is not the same as base currency

Cannot make expense refund because the vendor's currency is not the same as base currency

I am trying to create expense refund. My base currency is CAD and vendor is USD. So when I pay to vendor I need to put in my base currency CAD, but if I try to create expense refund I cannot because of the "
  • The customer's currency does not match with the base currency or the currency used in the transaction. Hence, this transaction cannot be recorded."
I cannot create refund in USD and I cannot change vendor's currency. So what am I supposed to do?