Add 'head' table
diff --git a/src/hb-open-type-private.hh b/src/hb-open-type-private.hh
index 4fc82dd..2ab639c 100644
--- a/src/hb-open-type-private.hh
+++ b/src/hb-open-type-private.hh
@@ -120,7 +120,7 @@
  */
 
 /* Global nul-content Null pool.  Enlarge as necessary. */
-static const void *_NullPool[16 / sizeof (void *)];
+static const void *_NullPool[64 / sizeof (void *)];
 
 /* Generic nul-content Null objects. */
 template <typename Type>