diff --git a/drivers/rtc/rtc-max6902.c b/drivers/rtc/rtc-max6902.c
index 0b20dfa..d941707 100644
--- a/drivers/rtc/rtc-max6902.c
+++ b/drivers/rtc/rtc-max6902.c
@@ -136,7 +136,7 @@
 	dt->tm_min	= BCD2BIN(chip->buf[2]);
 	dt->tm_hour	= BCD2BIN(chip->buf[3]);
 	dt->tm_mday	= BCD2BIN(chip->buf[4]);
-	dt->tm_mon	= BCD2BIN(chip->buf[5] - 1);
+	dt->tm_mon	= BCD2BIN(chip->buf[5]) - 1;
 	dt->tm_wday	= BCD2BIN(chip->buf[6]);
 	dt->tm_year = BCD2BIN(chip->buf[7]);