diff -r 9308d52205a0 -r bab29bcec7fe src/ObjectVisitor.h
--- a/src/ObjectVisitor.h	Sun Sep 16 19:02:23 2012 -0700
+++ b/src/ObjectVisitor.h	Sun Sep 16 21:34:10 2012 -0700
@@ -117,14 +117,9 @@
     }
 
     size_t iterateArray(Array *array, ArrayMap *map) {
-        assert(map->type()->isArray());
-        if (map->type()->contained()->isTraceable()) {
-            unsigned length = array->length();
-            Object **vec = array->objVec();
-            for (unsigned i = 0; i < length; i++)
-                this->visit(vec + i);
-        }
-        return Array::SizeOf(array);
+        if (!map->type()->fixedLength() || map->type()->contained()->isTraceable())
+            visitField(array, Array::offsetOfElements());
+        return array->objSize(map);
     }
 
     size_t iterateBox(Box *obj) {
@@ -289,7 +284,7 @@
         return sizeof(Native);
 
       case MapKind_Array:
-        return Align(Array::SizeOf(Array::cast(obj)), kObjectAlignment);
+        return Align(Array::cast(obj)->objSize(ArrayMap::cast(map)), kObjectAlignment);
 
       case MapKind_Box:
         return sizeof(Box);