diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 4c922ef634f8e81b5c45ce4dfcdf4f31722f03ca..92a57cf10fba4a05d797b7308404a66255263824 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -1586,7 +1586,8 @@ static int at91_adc_read_info_raw(struct iio_dev *indio_dev,
 		*val = st->conversion_value;
 		ret = at91_adc_adjust_val_osr(st, val);
 		if (chan->scan_type.sign == 's')
-			*val = sign_extend32(*val, 11);
+			*val = sign_extend32(*val,
+					     chan->scan_type.realbits - 1);
 		st->conversion_done = false;
 	}