diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 8518fa2..afe0f6d 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -20,7 +20,7 @@
 struct plat_serial8250_port {
 	unsigned long	iobase;		/* io base address */
 	void __iomem	*membase;	/* ioremap cookie or NULL */
-	unsigned long	mapbase;	/* resource base */
+	resource_size_t	mapbase;	/* resource base */
 	unsigned int	irq;		/* interrupt number */
 	unsigned int	uartclk;	/* UART clock rate */
 	unsigned char	regshift;	/* register shift */