diff --git a/documentation/ref-manual/ref-classes.xml b/documentation/ref-manual/ref-classes.xml
index 555918e80a..a219a930b9 100644
--- a/documentation/ref-manual/ref-classes.xml
+++ b/documentation/ref-manual/ref-classes.xml
@@ -2941,6 +2941,16 @@
         See the <filename>useradd-example.bb</filename> recipe for more
         information on how to use this class.
     </para>
+
+    <para>
+        The <filename>useradd</filename> class supports the
+        <link linkend='var-USERADD_PACKAGES'><filename>USERADD_PACKAGES</filename></link>,
+        <link linkend='var-USERADD_PARAM'><filename>USERADD_PARAM</filename></link>,
+        <link linkend='var-GROUPADD_PARAM'><filename>GROUPADD_PARAM</filename></link>,
+        and
+        <link linkend='var-GROUPMEMS_PARAM'><filename>GROUPMEMS_PARAM</filename></link>
+        variables.
+    </para>
 </section>
 
 <section id='ref-classes-utility-tasks'>