diff --git a/man/pam_systemd.xml b/man/pam_systemd.xml
index f81a4070bce..47f7439d317 100644
--- a/man/pam_systemd.xml
+++ b/man/pam_systemd.xml
@@ -213,17 +213,21 @@
                                 applications should not rely on this
                                 behavior and must be able to deal with
                                 stale files. To store session-private
-                                data in this directory, the user should
-                                include the value of <varname>$XDG_SESSION_ID</varname>
-                                in the filename. This directory shall
-                                be used for runtime file system
-                                objects such as <constant>AF_UNIX</constant> sockets,
-                                FIFOs, PID files and similar. It is
-                                guaranteed that this directory is
-                                local and offers the greatest possible
-                                file system feature set the
-                                operating system
-                                provides.</para></listitem>
+                                data in this directory, the user
+                                should include the value of
+                                <varname>$XDG_SESSION_ID</varname> in
+                                the filename. This directory shall be
+                                used for runtime file system objects
+                                such as <constant>AF_UNIX</constant>
+                                sockets, FIFOs, PID files and
+                                similar. It is guaranteed that this
+                                directory is local and offers the
+                                greatest possible file system feature
+                                set the operating system provides. For
+                                further details see the <ulink
+                                url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
+                                Base Directory
+                                Specification</ulink>.</para></listitem>
                         </varlistentry>
 
                 </variablelist>