diff --git a/drivers/mfd/sec-core.c b/drivers/mfd/sec-core.c
index 714e213..306b3a2 100644
--- a/drivers/mfd/sec-core.c
+++ b/drivers/mfd/sec-core.c
@@ -141,6 +141,8 @@
 static const struct regmap_config sec_rtc_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
+
+	.max_register = SEC_RTC_REG_MAX,
 };
 
 #ifdef CONFIG_OF