diff --git a/source/simulation2/components/ICmpPosition.h b/source/simulation2/components/ICmpPosition.h
index 3ccb8bf62a..b4be11d7f2 100644
--- a/source/simulation2/components/ICmpPosition.h
+++ b/source/simulation2/components/ICmpPosition.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2013 Wildfire Games.
+/* Copyright (C) 2014 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -24,6 +24,8 @@
 #include "maths/FixedVector3D.h"
 #include "maths/FixedVector2D.h"
 
+#include <set>
+
 class CMatrix3D;
 
 /**