diff --git a/client/OrbitCam.h b/client/OrbitCam.h
index 070a2db..95ac568 100644
--- a/client/OrbitCam.h
+++ b/client/OrbitCam.h
@@ -3,6 +3,7 @@
 #pragma once
 #include "NavigationCam.h"
 
+#include <functional>
 ///
 /// Controls:
 ///