diff --git a/functions/errorfunc.xml b/functions/errorfunc.xml
index bcb6a538e4..8af26bbcfe 100644
--- a/functions/errorfunc.xml
+++ b/functions/errorfunc.xml
@@ -97,6 +97,12 @@
       </tgroup>
      </table>
     </para>
+    <warning>
+     <para>
+      Remote debugging via TCP/IP is a PHP 3 feature that is <emphasis>not</emphasis>
+      availiable in PHP 4.
+     </para>
+    </warning>
     <para>
      <example role="php">
       <title><function>error_log</function> examples</title>