diff --git a/drivers/gpio/gpio-104-idio-16.c b/drivers/gpio/gpio-104-idio-16.c
index ffe7e1cb6b23..fe5c10cd5c32 100644
--- a/drivers/gpio/gpio-104-idio-16.c
+++ b/drivers/gpio/gpio-104-idio-16.c
@@ -59,6 +59,7 @@ static const struct regmap_config idio_16_regmap_config = {
 	.reg_stride = 1,
 	.val_bits = 8,
 	.io_port = true,
+	.max_register = 0x5,
 	.wr_table = &idio_16_wr_table,
 	.rd_table = &idio_16_rd_table,
 	.volatile_table = &idio_16_rd_table,