diff --git a/reactos/include/crt/dos.h b/reactos/include/crt/dos.h
index 3b3ac7d8af7..867326ab176 100644
--- a/reactos/include/crt/dos.h
+++ b/reactos/include/crt/dos.h
@@ -30,8 +30,9 @@ extern "C" {
 #define _A_RDONLY 0x01
 #define _A_HIDDEN 0x02
 #define _A_SYSTEM 0x04
+#define _A_VOLID  0x08
 #define _A_SUBDIR 0x10
-#define _A_ARCH 0x20
+#define _A_ARCH   0x20
 
 #ifndef _GETDISKFREE_DEFINED
 #define _GETDISKFREE_DEFINED