diff --git a/drivers/acpi/acpica/hwxface.c b/drivers/acpi/acpica/hwxface.c
index 6f98d210e71c..f75f81ad15c9 100644
--- a/drivers/acpi/acpica/hwxface.c
+++ b/drivers/acpi/acpica/hwxface.c
@@ -80,14 +80,14 @@ acpi_status acpi_reset(void)
 
 	if (reset_reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
 		/*
-		 * For I/O space, write directly to the OSL. This bypasses the port
-		 * validation mechanism, which may block a valid write to the reset
-		 * register.
+		 * For I/O space, write directly to the OSL. This
+		 * bypasses the port validation mechanism, which may
+		 * block a valid write to the reset register. Spec
+		 * section 4.7.3.6 requires register width to be 8.
 		 */
 		status =
 		    acpi_os_write_port((acpi_io_address) reset_reg->address,
-				       acpi_gbl_FADT.reset_value,
-				       reset_reg->bit_width);
+				       acpi_gbl_FADT.reset_value, 8);
 	} else {
 		/* Write the reset value to the reset register */