diff --git a/include/lib/aarch64/arch.h b/include/lib/aarch64/arch.h
index e5b2bf8..476c9c5 100644
--- a/include/lib/aarch64/arch.h
+++ b/include/lib/aarch64/arch.h
@@ -38,7 +38,9 @@
 #define MIDR_IMPL_MASK		0xff
 #define MIDR_IMPL_SHIFT		0x18
 #define MIDR_VAR_SHIFT		20
+#define MIDR_VAR_BITS		4
 #define MIDR_REV_SHIFT		0
+#define MIDR_REV_BITS		4
 #define MIDR_PN_MASK		0xfff
 #define MIDR_PN_SHIFT		0x4