diff --git a/documentation/ref-manual/ref-classes.xml b/documentation/ref-manual/ref-classes.xml
index 12bf49b811..ef38b4f92a 100644
--- a/documentation/ref-manual/ref-classes.xml
+++ b/documentation/ref-manual/ref-classes.xml
@@ -1112,6 +1112,25 @@
     </para>
 </section>
 
+<section id='ref-classes-mirrors'>
+    <title><filename>mirrors.bbclass</filename></title>
+
+    <para>
+        The mirrors (<filename>mirrors</filename>) class sets up some standard
+        <link linkend='var-MIRRORS'><filename>MIRRORS</filename></link> entries
+        for source code mirrors.
+        These mirrors provide a fall-back path in case the upstream source
+        specified in
+        <link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>
+        within recipes is unavailable.
+    </para>
+
+    <para>
+        This class is enabled by default since it is inherited by the
+        <link linkend='ref-classes-base'><filename>base</filename></link> class.
+    </para>
+</section>
+
 <section id='ref-classes-pkgconfig'>
     <title>Pkg-config - <filename>pkgconfig.bbclass</filename></title>