diff --git a/src/object_gui.cpp b/src/object_gui.cpp
--- a/src/object_gui.cpp
+++ b/src/object_gui.cpp
@@ -662,7 +662,7 @@ BuildObjectWindow::GUIObjectClassList::F
 	&TagNameFilter,
 };
 
-static const NWidgetPart _nested_build_object_widgets[] = {
+static constexpr NWidgetPart _nested_build_object_widgets[] = {
 	NWidget(NWID_HORIZONTAL),
 		NWidget(WWT_CLOSEBOX, COLOUR_DARK_GREEN),
 		NWidget(WWT_CAPTION, COLOUR_DARK_GREEN), SetDataTip(STR_OBJECT_BUILD_CAPTION, STR_TOOLTIP_WINDOW_TITLE_DRAG_THIS),