diff --git a/base/Lie-inl.h b/base/Lie-inl.h
index 1ebded962..616ac0702 100644
--- a/base/Lie-inl.h
+++ b/base/Lie-inl.h
@@ -5,6 +5,8 @@
  *      Author: richard
  */
 
+#pragma once
+
 #include "Lie.h"
 
 #define INSTANTIATE_LIE(T) \