diff --git a/etk/math/Vector4D.h b/etk/math/Vector4D.h
index a4c4cdb..2da1ba5 100644
--- a/etk/math/Vector4D.h
+++ b/etk/math/Vector4D.h
@@ -5,6 +5,7 @@
  * 
  * @license APACHE v2.0 (see license file)
  */
+#pragma once
 
 #include <etk/types.h>