diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 31dc080f2437b6b02dde206b1e7c5343100fdde9..ff85619a97325fc0f1fa64a8896cbb8cc417d3cc 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -351,7 +351,7 @@
 
 /* Bitfields in MID */
 #define MACB_IDNUM_OFFSET			16
-#define MACB_IDNUM_SIZE				16
+#define MACB_IDNUM_SIZE				12
 #define MACB_REV_OFFSET				0
 #define MACB_REV_SIZE				16