diff --git a/reactos/include/psdk/winbase.h b/reactos/include/psdk/winbase.h
index 6846b69a7c4..cfd340cccf2 100644
--- a/reactos/include/psdk/winbase.h
+++ b/reactos/include/psdk/winbase.h
@@ -585,6 +585,8 @@ extern "C" {
 #define CONDITION_VARIABLE_LOCKMODE_SHARED  RTL_CONDITION_VARIABLE_LOCKMODE_SHARED
 #endif
 
+#define INIT_ONCE_STATIC_INIT RTL_RUN_ONCE_INIT
+
 #ifndef RC_INVOKED
 
 #ifndef _FILETIME_
@@ -3772,6 +3774,15 @@ CopyFile2(
 
 #endif /* _WIN32_WINNT >= 0x0601 */
 
+WINBASEAPI
+BOOL
+WINAPI
+InitOnceExecuteOnce(
+  _Inout_ PINIT_ONCE InitOnce,
+  _In_ __callback PINIT_ONCE_FN InitFn,
+  _Inout_opt_ PVOID Parameter,
+  _Outptr_opt_result_maybenull_ LPVOID *Context);
+
 #ifdef _MSC_VER
 #pragma warning(pop)
 #endif