diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 3b2f6c04855e..e27f216361fc 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -241,7 +241,7 @@ typedef unsigned int __bitwise__ upf_t;
 
 struct uart_port {
 	spinlock_t		lock;			/* port lock */
-	unsigned int		iobase;			/* in/out[bwl] */
+	unsigned long		iobase;			/* in/out[bwl] */
 	unsigned char __iomem	*membase;		/* read/write[bwl] */
 	unsigned int		irq;			/* irq number */
 	unsigned int		uartclk;		/* base uart clock */