Index: linux/net/ieee80211/ieee80211_module.c
===================================================================
--- linux.orig/net/ieee80211/ieee80211_module.c	2006-09-25 22:37:20.000000000 +0200
+++ linux/net/ieee80211/ieee80211_module.c	2006-09-25 22:39:07.000000000 +0200
@@ -118,6 +118,14 @@
 			      &ieee->network_free_list);
 }
 
+static int ieee80211_change_mtu(struct net_device *dev, int new_mtu)
+{
+	if ((new_mtu < 68) || (new_mtu > 2400))
+		return -EINVAL;
+	dev->mtu = new_mtu;
+	return 0;
+}
+
 struct net_device *alloc_ieee80211(int sizeof_priv)
 {
 	struct ieee80211_device *ieee;
@@ -133,6 +141,7 @@
 	}
 	ieee = netdev_priv(dev);
 	dev->hard_start_xmit = ieee80211_xmit;
+	dev->change_mtu = ieee80211_change_mtu;
 
 	ieee->dev = dev;