diff --git a/src/acpi/acpi.c b/src/acpi/acpi.c
index e30b7d32cd..e357f6a87d 100644
--- a/src/acpi/acpi.c
+++ b/src/acpi/acpi.c
@@ -117,12 +117,11 @@ static enum cb_err acpi_fill_header(acpi_header_t *header, const char name[4],
 	return CB_SUCCESS;
 }
 
-static int acpi_create_mcfg_mmconfig(acpi_mcfg_mmconfig_t *mmconfig, u32 base,
+static int acpi_create_mcfg_mmconfig(acpi_mcfg_mmconfig_t *mmconfig, u64 base,
 				u16 seg_nr, u8 start, u8 end)
 {
 	memset(mmconfig, 0, sizeof(*mmconfig));
 	mmconfig->base_address = base;
-	mmconfig->base_reserved = 0;
 	mmconfig->pci_segment_group_number = seg_nr;
 	mmconfig->start_bus_number = start;
 	mmconfig->end_bus_number = end;
diff --git a/src/include/acpi/acpi.h b/src/include/acpi/acpi.h
index 33bd735c57..3a7c99c5a0 100644
--- a/src/include/acpi/acpi.h
+++ b/src/include/acpi/acpi.h
@@ -217,8 +217,7 @@ typedef struct acpi_tpm2 {
 } __packed acpi_tpm2_t;
 
 typedef struct acpi_mcfg_mmconfig {
-	u32 base_address;
-	u32 base_reserved;
+	u64 base_address;
 	u16 pci_segment_group_number;
 	u8 start_bus_number;
 	u8 end_bus_number;