diff --git a/defer.hpp b/defer.hpp
index a5f1a83..4c6e1d3 100644
--- a/defer.hpp
+++ b/defer.hpp
@@ -1,4 +1,5 @@
-#define DEFER_HEADER
+#pragma once
+
 template <typename T>
 struct DEFER_ExitScope {
     T lambda;