diff --git a/drivers/iio/adc/ad4000.c b/drivers/iio/adc/ad4000.c
index 93ecaf401f27..5609a7845b6f 100644
--- a/drivers/iio/adc/ad4000.c
+++ b/drivers/iio/adc/ad4000.c
@@ -942,7 +942,7 @@ static int ad4000_prepare_3wire_mode_message(struct ad4000_state *st,
 	xfers[0].cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
 
 	xfers[1].rx_buf = &st->scan.data;
-	xfers[1].len = BITS_TO_BYTES(chan->scan_type.storagebits);
+	xfers[1].len = chan->scan_type.realbits > 16 ? 4 : 2;
 
 	/*
 	 * If the device is set up for SPI offloading, IIO channel scan_type is