diff --git a/src/hb-null.hh b/src/hb-null.hh
index ca7492ebe..5ab3289eb 100644
--- a/src/hb-null.hh
+++ b/src/hb-null.hh
@@ -49,19 +49,19 @@ static inline Type const & Null (void) {
 }
 #define Null(Type) Null<Type>()
 
-/* Specializaiton for arbitrary-content arbitrary-sized Null objects. */
+/* Specializaitons for arbitrary-content Null objects expressed in bytes. */
 #define DECLARE_NULL_NAMESPACE_BYTES(Namespace, Type) \
 } /* Close namespace. */ \
-extern HB_INTERNAL const unsigned char _hb_Null_##Namespace##_##Type[sizeof (Namespace::Type)]; \
+extern HB_INTERNAL const unsigned char _hb_Null_##Namespace##_##Type[Namespace::Type::min_size]; \
 template <> \
 /*static*/ inline const Namespace::Type& Null<Namespace::Type> (void) { \
   return *reinterpret_cast<const Namespace::Type *> (_hb_Null_##Namespace##_##Type); \
 } \
 namespace Namespace { \
-static_assert (Namespace::Type::min_size <= sizeof (Type), "Null pool too small.  Enlarge."); \
+static_assert (true, "Just so we take semicolon after.")
 
 #define DEFINE_NULL_NAMESPACE_BYTES(Namespace, Type) \
-const unsigned char _hb_Null_##Namespace##_##Type[sizeof (Namespace::Type)]
+const unsigned char _hb_Null_##Namespace##_##Type[Namespace::Type::min_size]
 
 
 /* Global writable pool.  Enlarge as necessary. */