diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index ecb2d90c9c06d19536ce3400f15b38b4adb5b7be..f2d8bd5deac9ce47db013085e4166b46933fb6cf 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -171,7 +171,7 @@ struct at91_adc_state {
 	struct clk			*per_clk;
 	struct regulator		*reg;
 	struct regulator		*vref;
-	u32				vref_uv;
+	int				vref_uv;
 	const struct iio_chan_spec	*chan;
 	bool				conversion_done;
 	u32				conversion_value;