diff --git a/drivers/serial/mcf.c b/drivers/serial/mcf.c
index 051fcc2f5ba..e76fc72c9b3 100644
--- a/drivers/serial/mcf.c
+++ b/drivers/serial/mcf.c
@@ -434,7 +434,7 @@ static struct uart_ops mcf_uart_ops = {
 
 static struct mcf_uart mcf_ports[3];
 
-#define	MCF_MAXPORTS	(sizeof(mcf_ports) / sizeof(struct mcf_uart))
+#define	MCF_MAXPORTS	ARRAY_SIZE(mcf_ports)
 
 /****************************************************************************/
 #if defined(CONFIG_SERIAL_MCF_CONSOLE)