diff --git a/simplecpp.h b/simplecpp.h
index f495eff..df0f285 100755
--- a/simplecpp.h
+++ b/simplecpp.h
@@ -1,4 +1,4 @@
-/*
+/* -*- C++ -*-
  * simplecpp - A simple and high-fidelity C/C++ preprocessor library
  * Copyright (C) 2016-2023 simplecpp team
  */