diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index 72b03c328198..b917b9d5f710 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -572,8 +572,7 @@ static int crb_acpi_add(struct acpi_device *device)
 				ACPI_TPM2_COMMAND_BUFFER_WITH_SMC);
 			return -EINVAL;
 		}
-		crb_smc = ACPI_ADD_PTR(struct tpm2_crb_smc, buf,
-				       ACPI_TPM2_START_METHOD_PARAMETER_OFFSET);
+		crb_smc = ACPI_ADD_PTR(struct tpm2_crb_smc, buf, sizeof(*buf));
 		priv->smc_func_id = crb_smc->smc_func_id;
 		priv->flags |= CRB_FL_CRB_SMC_START;
 	}
diff --git a/include/acpi/actbl2.h b/include/acpi/actbl2.h
index 2b4af0769a28..0ff3c64ce924 100644
--- a/include/acpi/actbl2.h
+++ b/include/acpi/actbl2.h
@@ -1296,8 +1296,6 @@ struct acpi_table_tpm2 {
 #define ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD  8
 #define ACPI_TPM2_COMMAND_BUFFER_WITH_SMC          11
 
-#define ACPI_TPM2_START_METHOD_PARAMETER_OFFSET    52
-
 /*******************************************************************************
  *
  * UEFI - UEFI Boot optimization Table