diff --git a/include/pocketpy/common/_log_spline_tbl.h b/include/pocketpy/common/_log_spline_tbl.h
index 3b2abc48..fd1479b5 100644
--- a/include/pocketpy/common/_log_spline_tbl.h
+++ b/include/pocketpy/common/_log_spline_tbl.h
@@ -1,3 +1,5 @@
+#pragma once
+
 /* 
    Copyright (c) 2012,2013   Axel Kohlmeyer <akohlmey@gmail.com> 
    All rights reserved.