diff --git a/sys/dev/uart/uart_dev_ns8250.c b/sys/dev/uart/uart_dev_ns8250.c
--- a/sys/dev/uart/uart_dev_ns8250.c
+++ b/sys/dev/uart/uart_dev_ns8250.c
@@ -792,13 +792,11 @@
 int
 ns8250_bus_probe(struct uart_softc *sc)
 {
-	struct ns8250_softc *ns8250;
 	struct uart_bas *bas;
 	int count, delay, error, limit;
 	uint8_t lsr, mcr, ier;
 	uint8_t val;
 
-	ns8250 = (struct ns8250_softc *)sc;
 	bas = &sc->sc_bas;
 
 	error = ns8250_probe(bas);
@@ -893,7 +891,8 @@
 		    --limit)
 			DELAY(delay);
 		if (limit == 0) {
-			ier = uart_getreg(bas, REG_IER) & ns8250->ier_mask;
+			/* See the comment in ns8250_init(). */
+			ier = uart_getreg(bas, REG_IER) & 0xe0;
 			uart_setreg(bas, REG_IER, ier);
 			uart_setreg(bas, REG_MCR, mcr);
 			val = 0;