diff --git a/doc/manual/writing-nix-expressions.xml b/doc/manual/writing-nix-expressions.xml
index 4b6574288..3e6cd7379 100644
--- a/doc/manual/writing-nix-expressions.xml
+++ b/doc/manual/writing-nix-expressions.xml
@@ -782,6 +782,9 @@ stdenv.mkDerivation {
   <literal>true</literal> and
   <literal>false</literal>.</para></listitem>
 
+  <listitem><para>The null value, denoted as
+  <literal>null</literal>.</para></listitem>
+
 </itemizedlist>
 
 </para>