diff --git a/bitbake/doc/user-manual/user-manual-ref-variables.xml b/bitbake/doc/user-manual/user-manual-ref-variables.xml
index ff2d59a6e6..907e6c608c 100644
--- a/bitbake/doc/user-manual/user-manual-ref-variables.xml
+++ b/bitbake/doc/user-manual/user-manual-ref-variables.xml
@@ -373,6 +373,8 @@
                     Git metadata, to be placed in the
                     <link linkend='var-DL_DIR'><filename>DL_DIR</filename></link>
                     directory.
+                    Anyone wishing to create a source mirror would want to
+                    enable this variable.
                 </para>
 
                 <para>