diff --git a/drivers/rtc/rtc-s35390a.c b/drivers/rtc/rtc-s35390a.c
index 00662dd28d66..9a931efd50d3 100644
--- a/drivers/rtc/rtc-s35390a.c
+++ b/drivers/rtc/rtc-s35390a.c
@@ -106,7 +106,7 @@ static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
  */
 static int s35390a_reset(struct s35390a *s35390a, char *status1)
 {
-	char buf;
+	u8 buf;
 	int ret;
 	unsigned initcount = 0;