diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index d14081c10c17487dd9b269090a6e8d999d8ae6b6..49fe586e3b1e42602787eee0b9ab003576fb5904 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -434,7 +434,7 @@ void acpi_os_set_prepare_sleep(int (*func)(u8 sleep_state,
 
 acpi_status acpi_os_prepare_sleep(u8 sleep_state,
 				  u32 pm1a_control, u32 pm1b_control);
-#if CONFIG_X86
+#ifdef CONFIG_X86
 void arch_reserve_mem_area(acpi_physical_address addr, size_t size);
 #else
 static inline void arch_reserve_mem_area(acpi_physical_address addr,