diff --git a/drivers/staging/comedi/drivers/addi_apci_1500.c b/drivers/staging/comedi/drivers/addi_apci_1500.c
index fc7db1de0b90..f15aa1f6b476 100644
--- a/drivers/staging/comedi/drivers/addi_apci_1500.c
+++ b/drivers/staging/comedi/drivers/addi_apci_1500.c
@@ -296,7 +296,7 @@ static int apci1500_di_inttrig_start(struct comedi_device *dev,
 	unsigned int pa_mode = Z8536_PAB_MODE_PMS_DISABLE;
 	unsigned int pb_mode = Z8536_PAB_MODE_PMS_DISABLE;
 	unsigned int pa_trig = trig_num & 0x01;
-	unsigned int pb_trig = trig_num & 0x02;
+	unsigned int pb_trig = (trig_num >> 1) & 0x01;
 	bool valid_trig = false;
 	unsigned int val;