diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 51ceaee98f9f..e1e7143ca1e3 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -335,7 +335,7 @@ static void cciss_map_sg_chain_block(ctlr_info_t *h, CommandList_struct *c,
 static const char *raid_label[] = { "0", "4", "1(1+0)", "5", "5+1", "ADG",
 	"UNKNOWN"
 };
-#define RAID_UNKNOWN (sizeof(raid_label) / sizeof(raid_label[0])-1)
+#define RAID_UNKNOWN (ARRAY_SIZE(raid_label)-1)
 
 #ifdef CONFIG_PROC_FS