diff --git a/Servers/WindowServer/WSWindowFrame.h b/Servers/WindowServer/WSWindowFrame.h
index 7ed541e4cc..b58aec77b9 100644
--- a/Servers/WindowServer/WSWindowFrame.h
+++ b/Servers/WindowServer/WSWindowFrame.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <AK/OwnPtr.h>
 #include <AK/Vector.h>
 
 class Painter;