diff --git a/drivers/iio/adc/viperboard_adc.c b/drivers/iio/adc/viperboard_adc.c
index 9bb0b83c8f67..6efe1c618ef7 100644
--- a/drivers/iio/adc/viperboard_adc.c
+++ b/drivers/iio/adc/viperboard_adc.c
@@ -70,8 +70,10 @@ static int vprbrd_iio_read_raw(struct iio_dev *iio_dev,
 			VPRBRD_USB_TYPE_OUT, 0x0000, 0x0000, admsg,
 			sizeof(struct vprbrd_adc_msg), VPRBRD_USB_TIMEOUT_MS);
 		if (ret != sizeof(struct vprbrd_adc_msg)) {
-			dev_err(&iio_dev->dev, "usb send error on adc read\n");
+			mutex_unlock(&vb->lock);
 			error = -EREMOTEIO;
+			dev_err(&iio_dev->dev, "usb send error on adc read\n");
+			goto error;
 		}
 
 		ret = usb_control_msg(vb->usb_dev,