diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index f1c8ca6..c909984 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -407,6 +407,11 @@
 }
 #endif
 
+#else	/* CONFIG_ACPI */
+
+static int register_acpi_bus_type(struct acpi_bus_type *bus) { return 0; }
+static int unregister_acpi_bus_type(struct acpi_bus_type *bus) { return 0; }
+
 #endif				/* CONFIG_ACPI */
 
 #endif /*__ACPI_BUS_H__*/