diff --git a/reactos/w32api/include/objbase.h b/reactos/w32api/include/objbase.h
index 2dd51245a81..22f2cdd1725 100644
--- a/reactos/w32api/include/objbase.h
+++ b/reactos/w32api/include/objbase.h
@@ -39,6 +39,7 @@
 #define STGM_CREATE 0x1000
 #define STGM_CONVERT 0x20000
 #define STGM_NOSNAPSHOT 0x200000
+#define STGM_DIRECT_SWMR 0x400000
 #define STGM_FAILIFTHERE 0
 #define CWCSTORAGENAME 32
 #define ASYNC_MODE_COMPATIBILITY	1