diff --git a/drivers/gpio/gpio-pci-idio-16.c b/drivers/gpio/gpio-pci-idio-16.c
index 44c0a21b1d1d..5827b18d190b 100644
--- a/drivers/gpio/gpio-pci-idio-16.c
+++ b/drivers/gpio/gpio-pci-idio-16.c
@@ -41,6 +41,7 @@ static const struct regmap_config idio_16_regmap_config = {
 	.reg_stride = 1,
 	.val_bits = 8,
 	.io_port = true,
+	.max_register = 0x7,
 	.wr_table = &idio_16_wr_table,
 	.rd_table = &idio_16_rd_table,
 	.volatile_table = &idio_16_rd_table,