Index: uspace/drv/bus/usb/vhc/transfer.c
===================================================================
--- uspace/drv/bus/usb/vhc/transfer.c	(revision 5203e2569a38ea677d1b3f202650bb36f9609583)
+++ uspace/drv/bus/usb/vhc/transfer.c	(revision d9b2c73fe60c8358e376ab8fb1054d86149b1063)
@@ -206,10 +206,9 @@
 
 	if (transfer->direction == USB_DIRECTION_IN) {
-		transfer->callback_in(transfer->ddf_fun, outcome,
+		transfer->callback_in(outcome,
 		    data_transfer_size, transfer->callback_arg);
 	} else {
 		assert(transfer->direction == USB_DIRECTION_OUT);
-		transfer->callback_out(transfer->ddf_fun, outcome,
-		    transfer->callback_arg);
+		transfer->callback_out(outcome, transfer->callback_arg);
 	}