diff -up hplip-3.12.11/io/hpmud/musb.c.hplip-IEEE-1284-4 hplip-3.12.11/io/hpmud/musb.c
--- hplip-3.12.11/io/hpmud/musb.c.hplip-IEEE-1284-4	2012-11-20 10:55:09.000000000 +0100
+++ hplip-3.12.11/io/hpmud/musb.c	2012-11-27 11:49:16.633107366 +0100
@@ -712,7 +712,8 @@ static libusb_device *get_libusb_device(
 				{
 					if ((altptr->bInterfaceClass == LIBUSB_CLASS_PRINTER ) && /* Printer */
 							(altptr->bInterfaceSubClass == 1) &&
-							(altptr->bInterfaceProtocol == 1 || altptr->bInterfaceProtocol == 2)) /* Unidirectional or Bidirectional*/
+							(altptr->bInterfaceProtocol == 1 || altptr->bInterfaceProtocol == 2
+							|| altptr->bInterfaceProtocol == 3)) /* Unidirectional, Bidirectional or 1284.4 */
 					{
 						if (is_uri(dev, uri))
 						{
@@ -2065,7 +2066,8 @@ int __attribute__ ((visibility ("hidden"
 				{
 					if ((altptr->bInterfaceClass == LIBUSB_CLASS_PRINTER ) && /* Printer */
 							(altptr->bInterfaceSubClass == 1) &&
-							(altptr->bInterfaceProtocol == 1 || altptr->bInterfaceProtocol == 2)) /* Unidirectional or Bidirectional*/
+							(altptr->bInterfaceProtocol == 1 || altptr->bInterfaceProtocol == 2
+							|| altptr->bInterfaceProtocol == 3)) /* Unidirectional, Bidirectional or 1284.4 */
 					{
 						libusb_open(dev, &hd);
 						if (hd == NULL)