diff --git a/inc/dd.h b/inc/dd.h
index 8a074da..73a1202 100644
--- a/inc/dd.h
+++ b/inc/dd.h
@@ -54,6 +54,10 @@ HRESULT dd_CreateEx(GUID* lpGuid, LPVOID* lplpDD, REFIID iid, IUnknown* pUnkOute
 #define CREATE_WAITABLE_TIMER_HIGH_RESOLUTION 0x00000002
 #endif
 
+#ifndef CREATE_WAITABLE_TIMER_MANUAL_RESET
+#define CREATE_WAITABLE_TIMER_MANUAL_RESET 0x00000001
+#endif
+
 typedef struct SPEEDLIMITER
 {
     DWORD tick_length;