diff --git a/docs/UPnP.xml b/docs/UPnP.xml
index 3cb80c52c..7b62fe7fa 100644
--- a/docs/UPnP.xml
+++ b/docs/UPnP.xml
@@ -109,6 +109,11 @@ forwardUPnP        net     loc</programlisting>
       this route during <command>start</command> and deletes it during
       <command>stop</command>.</para>
     </note>
+
+    <caution>
+      <para>Shorewall versions prior to 4.4.10 do not retain the dynamic rules
+      added by linux-idg over a <command>shorewall restart</command>.</para>
+    </caution>
   </section>
 
   <section>