diff --git a/drivers/staging/comedi/drivers/addi_apci_1564.c b/drivers/staging/comedi/drivers/addi_apci_1564.c
index f91aedd9c869..1e25342ebc81 100644
--- a/drivers/staging/comedi/drivers/addi_apci_1564.c
+++ b/drivers/staging/comedi/drivers/addi_apci_1564.c
@@ -391,7 +391,7 @@ static int apci1564_auto_attach(struct comedi_device *dev,
 	s->type = COMEDI_SUBD_DO;
 	s->subdev_flags = SDF_WRITEABLE;
 	s->n_chan = 32;
-	s->maxdata = 0xffffffff;
+	s->maxdata = 1;
 	s->range_table = &range_digital;
 	s->insn_config = apci1564_do_config;
 	s->insn_bits = apci1564_do_insn_bits;