diff --git a/drivers/iio/addac/stx104.c b/drivers/iio/addac/stx104.c
index 29c47c33c7dc..8237ae4263cb 100644
--- a/drivers/iio/addac/stx104.c
+++ b/drivers/iio/addac/stx104.c
@@ -117,6 +117,8 @@ static int stx104_read_raw(struct iio_dev *indio_dev,
 			return IIO_VAL_INT;
 		}
 
+		mutex_lock(&priv->lock);
+
 		/* select ADC channel */
 		iowrite8(chan->channel | (chan->channel << 4), &reg->achan);
 
@@ -127,6 +129,8 @@ static int stx104_read_raw(struct iio_dev *indio_dev,
 		while (ioread8(&reg->cir_asr) & BIT(7));
 
 		*val = ioread16(&reg->ssr_ad);
+
+		mutex_unlock(&priv->lock);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_OFFSET:
 		/* get ADC bipolar/unipolar configuration */