diff --git a/include/lib/aarch64/arch.h b/include/lib/aarch64/arch.h
index 49efafc..a9b2dbb 100644
--- a/include/lib/aarch64/arch.h
+++ b/include/lib/aarch64/arch.h
@@ -419,11 +419,11 @@
 #define AP_RW			(0x0 << 5)
 
 #define NS				(0x1 << 3)
-#define ATTR_SO_INDEX			0x2
+#define ATTR_NON_CACHEABLE_INDEX	0x2
 #define ATTR_DEVICE_INDEX		0x1
 #define ATTR_IWBWA_OWBWA_NTR_INDEX	0x0
 #define LOWER_ATTRS(x)			(((x) & 0xfff) << 2)
-#define ATTR_SO				(0x0)
+#define ATTR_NON_CACHEABLE		(0x44)
 #define ATTR_DEVICE			(0x4)
 #define ATTR_IWBWA_OWBWA_NTR		(0xff)
 #define MAIR_ATTR_SET(attr, index)	(attr << (index << 3))
diff --git a/include/lib/aarch64/xlat_tables.h b/include/lib/aarch64/xlat_tables.h
index 0b5dbdf..d21100e 100644
--- a/include/lib/aarch64/xlat_tables.h
+++ b/include/lib/aarch64/xlat_tables.h
@@ -52,21 +52,41 @@
 #define MAP_REGION(pa, va, sz, attr) {(pa), (va), (sz), (attr)}
 
 /*
- * Flags for building up memory mapping attributes.
- * These are organised so that a clear bit gives a more restrictive  mapping
- * that a set bit, that way a bitwise-and two sets of attributes will never give
- * an attribute which has greater access rights that any of the original
- * attributes.
+ * Shifts and masks to access fields of an mmap_attr_t
+ */
+#define MT_TYPE_MASK	0x7
+#define MT_TYPE(_attr)	((_attr) & MT_TYPE_MASK)
+/* Access permissions (RO/RW) */
+#define MT_PERM_SHIFT	3
+/* Security state (SECURE/NS) */
+#define MT_SEC_SHIFT	4
+
+/*
+ * Memory mapping attributes
  */
 typedef enum  {
-	MT_DEVICE	= 0 << 0,
-	MT_MEMORY	= 1 << 0,
+	/*
+	 * Memory types supported.
+	 * These are organised so that, going down the list, the memory types
+	 * are getting weaker; conversely going up the list the memory types are
+	 * getting stronger.
+	 */
+	MT_DEVICE,
+	MT_NON_CACHEABLE,
+	MT_MEMORY,
+	/* Values up to 7 are reserved to add new memory types in the future */
 
-	MT_RO		= 0 << 1,
-	MT_RW		= 1 << 1,
+	/*
+	 * The following values are organised so that a clear bit gives a more
+	 * restrictive mapping than a set bit, that way a bitwise-and of two
+	 * sets of attributes will never give an attribute which has greater
+	 * access rights than any of the original attributes.
+	 */
+	MT_RO		= 0 << MT_PERM_SHIFT,
+	MT_RW		= 1 << MT_PERM_SHIFT,
 
-	MT_SECURE	= 0 << 2,
-	MT_NS		= 1 << 2
+	MT_SECURE	= 0 << MT_SEC_SHIFT,
+	MT_NS		= 1 << MT_SEC_SHIFT,
 } mmap_attr_t;
 
 /*