diff --git a/doc/manual/builtins.xml b/doc/manual/builtins.xml
index 9f5f4438ce..b75f58e21f 100644
--- a/doc/manual/builtins.xml
+++ b/doc/manual/builtins.xml
@@ -302,6 +302,18 @@ stdenv.mkDerivation {
   </varlistentry>
 
 
+  <varlistentry><term><function>builtins.hashString</function>
+  <replaceable>type</replaceable> <replaceable>s</replaceable></term>
+
+    <listitem><para>Return a base-16 representation of the
+    cryptographic hash of string <replaceable>s</replaceable>.  The
+    hash algorithm specified by <replaceable>type</replaceable> must
+    be one of <literal>"md5"</literal>, <literal>"sha1"</literal> or
+    <literal>"sha256"</literal>.</para></listitem>
+
+  </varlistentry>
+
+
   <varlistentry><term><function>builtins.head</function>
   <replaceable>list</replaceable></term>
 
diff --git a/doc/manual/release-notes.xml b/doc/manual/release-notes.xml
index e7e9bf3c5b..6f81e7223e 100644
--- a/doc/manual/release-notes.xml
+++ b/doc/manual/release-notes.xml
@@ -6,6 +6,20 @@
 
 
 
+<!--==================================================================-->
+
+<section xml:id="ssec-relnotes-1.4"><title>Release 1.4 (TBA)</title>
+
+<itemizedlist>
+
+  <listitem><para>New built-in function:
+  <function>builtins.hashString</function>.</para></listitem>
+
+</itemizedlist>
+
+</section>
+
+
 <!--==================================================================-->
 
 <section xml:id="ssec-relnotes-1.3"><title>Release 1.3 (January 4, 2013)</title>