diff --git a/Userland/Libraries/LibGUI/Forward.h b/Userland/Libraries/LibGUI/Forward.h
index 8abb348967..28208c1457 100644
--- a/Userland/Libraries/LibGUI/Forward.h
+++ b/Userland/Libraries/LibGUI/Forward.h
@@ -71,6 +71,7 @@ class Painter;
 class ResizeCorner;
 class ResizeEvent;
 class ScrollBar;
+class ScrollableWidget;
 class Slider;
 class SortingProxyModel;
 class SpinBox;