diff --git a/documentation/ref-manual/ref-classes.xml b/documentation/ref-manual/ref-classes.xml
index 5a75199387..05e0fa6ce3 100644
--- a/documentation/ref-manual/ref-classes.xml
+++ b/documentation/ref-manual/ref-classes.xml
@@ -865,6 +865,18 @@
     </para>
 </section>
 
+<section id='ref-classes-image-vmdk'>
+    <title><filename>image-vmdk.bbclass</filename></title>
+
+    <para>
+        The Virtual Machine Disk image (<filename>image-vmdk</filename>) class
+        supports building VMware VMDK images.
+        Normally, you do not use this class directly.
+        Instead, you add "vmdk" to
+        <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>.
+    </para>
+</section>
+
 <section id='ref-classes-mime'>
     <title><filename>mime.bbclass</filename></title>