diff --git a/reactos/include/crt/sec_api/stdlib_s.h b/reactos/include/crt/sec_api/stdlib_s.h
index 547589b8049..90831f67692 100644
--- a/reactos/include/crt/sec_api/stdlib_s.h
+++ b/reactos/include/crt/sec_api/stdlib_s.h
@@ -19,7 +19,7 @@ extern "C" {
   errno_t
   __cdecl
   _dupenv_s(
-    _Outptr_result_buffer_maybenull_(*_PBufferSizeInBytes) _Outptr_result_z_ char **_PBuffer,
+    _Outptr_result_buffer_maybenull_(*_PBufferSizeInBytes) _Outptr_result_maybenull_z_ char **_PBuffer,
     _Out_opt_ size_t *_PBufferSizeInBytes,
     _In_z_ const char *_VarName);
 
@@ -180,7 +180,7 @@ extern "C" {
   errno_t
   __cdecl
   _wdupenv_s(
-    _Outptr_result_buffer_maybenull_(*_BufferSizeInWords) _Outptr_result_z_ wchar_t **_Buffer,
+    _Outptr_result_buffer_maybenull_(*_BufferSizeInWords) _Outptr_result_maybenull_z_ wchar_t **_Buffer,
     _Out_opt_ size_t *_BufferSizeInWords,
     _In_z_ const wchar_t *_VarName);