diff --git a/docs/misc/xenstore-paths.pandoc b/docs/misc/xenstore-paths.pandoc
index 766e8008dc..5cd5c8a3b9 100644
--- a/docs/misc/xenstore-paths.pandoc
+++ b/docs/misc/xenstore-paths.pandoc
@@ -298,6 +298,9 @@ A virtual keyboard device frontend. Described by
 A virtual network device frontend. Described by
 [xen/include/public/io/netif.h][NETIF]
 
+NOTE: ~/device/vif/$DEVID/mtu can be used to inform the frontend of an
+      increased MTU. (The default MTU is 1500 octets).
+
 #### ~/device/vscsi/$DEVID/* []
 
 A virtual scsi device frontend. Described by
diff --git a/xen/include/public/io/netif.h b/xen/include/public/io/netif.h
index 9fcf91a2fe..00dd258712 100644
--- a/xen/include/public/io/netif.h
+++ b/xen/include/public/io/netif.h
@@ -204,6 +204,18 @@
  * present).
  */
 
+/*
+ * MTU
+ * ===
+ *
+ * The toolstack may set a value of MTU for the frontend by setting the
+ * /local/domain/<domid>/device/vif/<vif>/mtu node with the MTU value in
+ * octets. If this node is absent the frontend should assume an MTU value
+ * of 1500 octets. A frontend is also at liberty to ignore this value so
+ * it is only suitable for informing the frontend that a packet payload
+ * >1500 octets is permitted.
+ */
+
 /*
  * Hash types
  * ==========