diff --git a/cpp/LieConfig-inl.h b/cpp/LieConfig-inl.h
index 148da90ef..b3dbf5fb7 100644
--- a/cpp/LieConfig-inl.h
+++ b/cpp/LieConfig-inl.h
@@ -5,6 +5,8 @@
  *      Author: richard
  */
 
+#pragma once
+
 #include <boost/foreach.hpp>
 #include <boost/tuple/tuple.hpp>
 #include <utility>