diff --git a/moo/lib/moo-cmn.h b/moo/lib/moo-cmn.h
index af9bcba..125d2cb 100644
--- a/moo/lib/moo-cmn.h
+++ b/moo/lib/moo-cmn.h
@@ -628,6 +628,15 @@ typedef struct moo_t moo_t;
 #define MOO_TYPE_MIN(type) \
 	((MOO_TYPE_IS_SIGNED(type)? MOO_TYPE_SIGNED_MIN(type): MOO_TYPE_UNSIGNED_MIN(type)))
 
+/* round up a positive integer x to the nearst multiple of y */
+#define MOO_ALIGN(x,y) ((((x) + (y) - 1) / (y)) * (y))
+
+/* round up a positive integer x to the nearst multiple of y where
+ * y must be a multiple of a power of 2*/
+#define MOO_ALIGN_POW2(x,y) ((((x) + (y) - 1)) & ~((y) - 1))
+
+#define MOO_IS_UNALIGNED_POW2(x,y) ((x) & ((y) - 1))
+#define MOO_IS_ALIGNED_POW2(x,y) (!MOO_IS_UNALIGNED_POW2(x,y))
 
 /* =========================================================================
  * COMPILER FEATURE TEST MACROS
diff --git a/moo/lib/moo-prv.h b/moo/lib/moo-prv.h
index 43114c6..97dddd9 100644
--- a/moo/lib/moo-prv.h
+++ b/moo/lib/moo-prv.h
@@ -102,8 +102,6 @@
 #	define MOO_MEMCMP(dst,src,size)  memcmp(dst,src,size)
 #endif
 
-#define MOO_ALIGN(x,y) ((((x) + (y) - 1) / (y)) * (y))
-
 
 /* ========================================================================= */
 /* CLASS SPEC ENCODING                                                       */
@@ -113,7 +111,7 @@
  * The spec field of a class object encodes the number of the fixed part
  * and the type of the indexed part. The fixed part is the number of
  * named instance variables. If the spec of a class is indexed, the object
- * of the class can be i nstantiated with the size of the indexed part.
+ * of the class can be instantiated with the size of the indexed part.
  *
  * For example, on a platform where sizeof(moo_oow_t) is 4, 
  * the layout of the spec field of a class as an OOP value looks like this: