diff --git a/Documentation/NuttxPortingGuide.html b/Documentation/NuttxPortingGuide.html
index a750a04a2f6..9cf518cb528 100644
--- a/Documentation/NuttxPortingGuide.html
+++ b/Documentation/NuttxPortingGuide.html
@@ -2921,6 +2921,9 @@ build
   <li>
     <code>CONFIG_NET_ARPTAB_SIZE</code>: The size of the ARP table
   </li>
+  <li>
+    <code>CONFIG_NET_ARP_IPIN</code>: Harvest IP/MAC address mappings for the ARP table from incoming IP packets.
+  </li>
   <li>
     <code>CONFIG_NET_BROADCAST</code>: Incoming UDP broadcast support
   </li>