diff --git a/drivers/dio/dio.c b/drivers/dio/dio.c
index 17502d6efae7..07f274f853d9 100644
--- a/drivers/dio/dio.c
+++ b/drivers/dio/dio.c
@@ -88,8 +88,6 @@ static struct dioname names[] =
 #undef DIONAME
 #undef DIOFBNAME
 
-#define NUMNAMES (sizeof(names) / sizeof(struct dioname))
-
 static const char *unknowndioname 
         = "unknown DIO board -- please email <linux-m68k@lists.linux-m68k.org>!";
 
@@ -97,7 +95,7 @@ static const char *dio_getname(int id)
 {
         /* return pointer to a constant string describing the board with given ID */
 	unsigned int i;
-        for (i = 0; i < NUMNAMES; i++)
+	for (i = 0; i < ARRAY_SIZE(names); i++)
                 if (names[i].id == id) 
                         return names[i].name;