diff --git a/src/include/ipxe/netdevice.h b/src/include/ipxe/netdevice.h
index a1d207ff..d498ab69 100644
--- a/src/include/ipxe/netdevice.h
+++ b/src/include/ipxe/netdevice.h
@@ -397,9 +397,16 @@ struct net_device {
 	struct retry_timer link_block;
 	/** Maximum packet length
 	 *
-	 * This length includes any link-layer headers.
+	 * This is the maximum packet length (including any link-layer
+	 * headers) supported by the hardware.
 	 */
 	size_t max_pkt_len;
+	/** Maximum transmission unit length
+	 *
+	 * This is the maximum transmission unit length (excluding any
+	 * link-layer headers) configured for the link.
+	 */
+	size_t mtu;
 	/** TX packet queue */
 	struct list_head tx_queue;
 	/** Deferred TX packet queue */
diff --git a/src/net/infiniband/xsigo.c b/src/net/infiniband/xsigo.c
index 91b7b71f..0ee753c3 100644
--- a/src/net/infiniband/xsigo.c
+++ b/src/net/infiniband/xsigo.c
@@ -323,6 +323,7 @@ static int xve_update_mtu ( struct xsigo_nic *xve, struct eoib_device *eoib,
 	 * not the EoIB header.
 	 */
 	netdev->max_pkt_len = ( mtu + sizeof ( struct ethhdr ) );
+	netdev->mtu = mtu;
 	DBGC ( xve, "XVE %s has MTU %zd\n", xve->name, mtu );
 
 	return 0;
diff --git a/src/net/netdev_settings.c b/src/net/netdev_settings.c
index 67a45bed..c54288d4 100644
--- a/src/net/netdev_settings.c
+++ b/src/net/netdev_settings.c
@@ -393,7 +393,8 @@ static int apply_netdev_settings ( void ) {
 	struct net_device *netdev;
 	struct settings *settings;
 	struct ll_protocol *ll_protocol;
-	size_t old_max_pkt_len;
+	size_t max_mtu;
+	size_t old_mtu;
 	size_t mtu;
 	int rc;
 
@@ -410,18 +411,25 @@ static int apply_netdev_settings ( void ) {
 		if ( ! mtu )
 			continue;
 
-		/* Update maximum packet length */
+		/* Limit MTU to maximum supported by hardware */
 		ll_protocol = netdev->ll_protocol;
-		old_max_pkt_len = netdev->max_pkt_len;
-		netdev->max_pkt_len = ( mtu + ll_protocol->ll_header_len );
-		if ( netdev->max_pkt_len != old_max_pkt_len ) {
+		max_mtu = ( netdev->max_pkt_len - ll_protocol->ll_header_len );
+		if ( mtu > max_mtu ) {
+			DBGC ( netdev, "NETDEV %s cannot support MTU %zd (max "
+			       "%zd)\n", netdev->name, mtu, max_mtu );
+			mtu = max_mtu;
+		}
+
+		/* Update maximum packet length */
+		old_mtu = netdev->mtu;
+		netdev->mtu = mtu;
+		if ( mtu != old_mtu ) {
 			DBGC ( netdev, "NETDEV %s MTU is %zd\n",
 			       netdev->name, mtu );
 		}
 
 		/* Close and reopen network device if MTU has increased */
-		if ( netdev_is_open ( netdev ) &&
-		     ( netdev->max_pkt_len > old_max_pkt_len ) ) {
+		if ( netdev_is_open ( netdev ) && ( mtu > old_mtu ) ) {
 			netdev_close ( netdev );
 			if ( ( rc = netdev_open ( netdev ) ) != 0 ) {
 				DBGC ( netdev, "NETDEV %s could not reopen: "
diff --git a/src/net/netdevice.c b/src/net/netdevice.c
index 9df21196..41ece77f 100644
--- a/src/net/netdevice.c
+++ b/src/net/netdevice.c
@@ -663,6 +663,12 @@ int register_netdev ( struct net_device *netdev ) {
 		ll_protocol->init_addr ( netdev->hw_addr, netdev->ll_addr );
 	}
 
+	/* Set MTU, if not already set */
+	if ( ! netdev->mtu ) {
+		netdev->mtu = ( netdev->max_pkt_len -
+				ll_protocol->ll_header_len );
+	}
+
 	/* Reject network devices that are already available via a
 	 * different hardware device.
 	 */
diff --git a/src/net/tcpip.c b/src/net/tcpip.c
index c9e4ee78..cc7d0200 100644
--- a/src/net/tcpip.c
+++ b/src/net/tcpip.c
@@ -144,8 +144,7 @@ size_t tcpip_mtu ( struct sockaddr_tcpip *st_dest ) {
 		return 0;
 
 	/* Calculate MTU */
-	mtu = ( netdev->max_pkt_len - netdev->ll_protocol->ll_header_len -
-		tcpip_net->header_len );
+	mtu = ( netdev->mtu - tcpip_net->header_len );
 
 	return mtu;
 }