diff --git a/include/grub/acpi.h b/include/grub/acpi.h
index 66148f684..84f49487d 100644
--- a/include/grub/acpi.h
+++ b/include/grub/acpi.h
@@ -93,7 +93,7 @@ struct grub_acpi_madt
   grub_uint32_t lapic_addr;
   grub_uint32_t flags;
   struct grub_acpi_madt_entry_header entries[0];
-};
+} GRUB_PACKED;
 
 enum
   {