diff -puN drivers/isdn/hysdn/hysdn_net.c~hysdn-fix-writing-outside-the-field-on-64-bits drivers/isdn/hysdn/hysdn_net.c
--- a/drivers/isdn/hysdn/hysdn_net.c~hysdn-fix-writing-outside-the-field-on-64-bits
+++ a/drivers/isdn/hysdn/hysdn_net.c
@@ -83,12 +83,12 @@ net_open(struct net_device *dev)
 
 	/* Fill in the MAC-level header (if not already set) */
 	if (!card->mac_addr[0]) {
-		for (i = 0; i < ETH_ALEN - sizeof(unsigned long); i++)
+		for (i = 0; i < ETH_ALEN; i++)
 			dev->dev_addr[i] = 0xfc;
 		if ((in_dev = dev->ip_ptr) != NULL) {
 			struct in_ifaddr *ifa = in_dev->ifa_list;
 			if (ifa != NULL)
-				memcpy(dev->dev_addr + (ETH_ALEN - sizeof(unsigned long)), &ifa->ifa_local, sizeof(unsigned long));
+				memcpy(dev->dev_addr + (ETH_ALEN - sizeof(ifa->ifa_local)), &ifa->ifa_local, sizeof(ifa->ifa_local));
 		}
 	} else
 		memcpy(dev->dev_addr, card->mac_addr, ETH_ALEN);