diff --git a/src/signs_gui.cpp b/src/signs_gui.cpp
--- a/src/signs_gui.cpp
+++ b/src/signs_gui.cpp
@@ -346,6 +346,7 @@ static const NWidgetPart _nested_sign_li
 		NWidget(WWT_CLOSEBOX, COLOUR_GREY),
 		NWidget(WWT_CAPTION, COLOUR_GREY, WID_SIL_CAPTION), SetDataTip(STR_SIGN_LIST_CAPTION, STR_TOOLTIP_WINDOW_TITLE_DRAG_THIS),
 		NWidget(WWT_SHADEBOX, COLOUR_GREY),
+		NWidget(WWT_DEFSIZEBOX, COLOUR_GREY),
 		NWidget(WWT_STICKYBOX, COLOUR_GREY),
 	EndContainer(),
 	NWidget(NWID_HORIZONTAL),