diff --git a/spec.html b/spec.html
index 23c168ada4..2296c38ec6 100644
--- a/spec.html
+++ b/spec.html
@@ -4507,6 +4507,7 @@ <h1>
         <dl class="header">
         </dl>
         <emu-alg>
+          1. If _size_ > 2<sup>53</sup> - 1, throw a *RangeError* exception.
           1. Let _db_ be a new Data Block value consisting of _size_ bytes. If it is impossible to create such a Data Block, throw a *RangeError* exception.
           1. Set all of the bytes of _db_ to 0.
           1. Return _db_.