diff --git a/drivers/ide/ide-acpi.c b/drivers/ide/ide-acpi.c
index 244a8a052ce8..fd4a36433050 100644
--- a/drivers/ide/ide-acpi.c
+++ b/drivers/ide/ide-acpi.c
@@ -615,10 +615,10 @@ void ide_acpi_push_timing(ide_hwif_t *hwif)
 	in_params[0].buffer.length = sizeof(struct GTM_buffer);
 	in_params[0].buffer.pointer = (u8 *)&hwif->acpidata->gtm;
 	in_params[1].type = ACPI_TYPE_BUFFER;
-	in_params[1].buffer.length = sizeof(ATA_ID_WORDS * 2);
+	in_params[1].buffer.length = ATA_ID_WORDS * 2;
 	in_params[1].buffer.pointer = (u8 *)&master->idbuff;
 	in_params[2].type = ACPI_TYPE_BUFFER;
-	in_params[2].buffer.length = sizeof(ATA_ID_WORDS * 2);
+	in_params[2].buffer.length = ATA_ID_WORDS * 2;
 	in_params[2].buffer.pointer = (u8 *)&slave->idbuff;
 	/* Output buffer: _STM has no output */