diff --git a/src/object_gui.cpp b/src/object_gui.cpp
index 31b7df2d25..cdbfdc70de 100644
--- a/src/object_gui.cpp
+++ b/src/object_gui.cpp
@@ -119,6 +119,7 @@ public:
 
 		NWidgetMatrix *matrix = this->GetWidget<NWidgetMatrix>(WID_BO_SELECT_MATRIX);
 		matrix->SetScrollbar(this->GetScrollbar(WID_BO_SELECT_SCROLL));
+		matrix->SetCount(ObjectClass::Get(_selected_object_class)->GetUISpecCount());
 
 		this->GetWidget<NWidgetMatrix>(WID_BO_OBJECT_MATRIX)->SetCount(4);