diff --git a/drivers/mtd/maps/dbox2-flash.c b/drivers/mtd/maps/dbox2-flash.c
index 49d9054..652813c 100644
--- a/drivers/mtd/maps/dbox2-flash.c
+++ b/drivers/mtd/maps/dbox2-flash.c
@@ -57,7 +57,7 @@
 	}
 };
 
-#define NUM_PARTITIONS (sizeof(partition_info) / sizeof(partition_info[0]))
+#define NUM_PARTITIONS ARRAY_SIZE(partition_info)
 
 #define WINDOW_ADDR 0x10000000
 #define WINDOW_SIZE 0x800000