diff --git a/zip-0224.html b/zip-0224.html
index 018b9e3b..7ba3cdc9 100644
--- a/zip-0224.html
+++ b/zip-0224.html
@@ -16,7 +16,12 @@ Owners: Daira Hopwood <daira@electriccoin.co>
 Status: Reserved
 Category: Consensus
 Discussions-To: &lt;<a href="https://github.com/zcash/zips/issues/435">https://github.com/zcash/zips/issues/435</a>&gt;</pre>
-        <p>This ZIP number is reserved. Preliminary technical content relating to Orchard is currently in the <a href="https://zcash.github.io/orchard/design.html">Orchard Book</a>, and in zcash/zcash GitHub tickets <a href="https://github.com/zcash/zcash/issues?q=label%3AA-Orchard">labeled A-Orchard</a>.</p>
+        <p>This ZIP number is reserved. Preliminary technical content relating to Orchard and Halo 2 are currently in:</p>
+        <ul>
+            <li>the <a href="https://zcash.github.io/orchard/design.html">Orchard Book</a>;</li>
+            <li>the <a href="https://zcash.github.io/halo2/">Halo Book</a>;</li>
+            <li>zcash/zcash GitHub tickets labeled <a href="https://github.com/zcash/zcash/issues?q=label%3AA-Orchard">A-Orchard</a> and <a href="https://github.com/zcash/zcash/issues?q=label%3AA-Halo">A-Halo</a>.</li>
+        </ul>
     </section>
 </body>
 </html>
\ No newline at end of file
diff --git a/zip-0224.rst b/zip-0224.rst
index 449fc1d4..2e969a3f 100644
--- a/zip-0224.rst
+++ b/zip-0224.rst
@@ -11,6 +11,10 @@
   Category: Consensus
   Discussions-To: <https://github.com/zcash/zips/issues/435>
 
-This ZIP number is reserved. Preliminary technical content relating to Orchard
-is currently in the `Orchard Book <https://zcash.github.io/orchard/design.html>`_, and in
-zcash/zcash GitHub tickets `labeled A-Orchard <https://github.com/zcash/zcash/issues?q=label%3AA-Orchard>`_.
+This ZIP number is reserved. Preliminary technical content relating to Orchard and Halo 2
+are currently in:
+
+* the `Orchard Book <https://zcash.github.io/orchard/design.html>`_;
+* the `Halo Book <https://zcash.github.io/halo2/>`_;
+* zcash/zcash GitHub tickets labeled `A-Orchard <https://github.com/zcash/zcash/issues?q=label%3AA-Orchard>`_
+  and `A-Halo <https://github.com/zcash/zcash/issues?q=label%3AA-Halo>`_.