diff --git a/docs/Shorewall_Squid_Usage.xml b/docs/Shorewall_Squid_Usage.xml
index c6ecf9379..8b8f5bdbd 100644
--- a/docs/Shorewall_Squid_Usage.xml
+++ b/docs/Shorewall_Squid_Usage.xml
@@ -20,6 +20,8 @@
     <copyright>
       <year>2003-2008</year>
 
+      <year>2017</year>
+
       <holder>Thomas M. Eastep</holder>
     </copyright>
 
@@ -45,6 +47,13 @@
     release.</emphasis></para>
   </caution>
 
+  <caution>
+    <para>If your firewall is dual-stack, there are risks to using either
+    Transparent Proxy or TPROXY. Both break PMTU discovery for local clients
+    and can cause slow page loading and/or inability to connect to some
+    sites.</para>
+  </caution>
+
   <section id="Transparent">
     <title>Squid as a Transparent (Interception) Proxy</title>