diff --git a/src/Xero.hs b/src/Xero.hs
index 7ddfb08..8d67b4f 100644
--- a/src/Xero.hs
+++ b/src/Xero.hs
@@ -418,6 +418,7 @@ payXeroInvoice pipe dbName inv address amt = do
                  [ "Invoice" .= object ["InvoiceNumber" .= inv]
                  , "Account" .= object ["Code" .= fromMaybe "" aCode]
                  , "Date" .= utctDay today
+                 , "Reference" .= ("Paid in Zcash through ZGo" :: String)
                  , "Amount" .= amt
                  ]) $
             addRequestHeader "Accept" "application/json" $