diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
index afe3d514b9..97bf098534 100644
--- a/xen/drivers/char/ns16550.c
+++ b/xen/drivers/char/ns16550.c
@@ -441,10 +441,12 @@ static void __init cf_check ns16550_init_postirq(struct serial_port *port)
             struct msi_info msi = {
                 .sbdf = PCI_SBDF(0, uart->ps_bdf[0], uart->ps_bdf[1],
                                  uart->ps_bdf[2]),
-                .irq = rc = uart->irq,
+                .irq = uart->irq,
                 .entry_nr = 1
             };
 
+            rc = uart->irq;
+
             if ( rc > 0 )
             {
                 struct msi_desc *msi_desc = NULL;