diff --git a/src/order_gui.cpp b/src/order_gui.cpp
--- a/src/order_gui.cpp
+++ b/src/order_gui.cpp
@@ -1297,7 +1297,7 @@ public:
 			case WID_O_COND_VARIABLE: {
 				DropDownList *list = new DropDownList();
 				for (uint i = 0; i < lengthof(_order_conditional_variable); i++) {
-					*list->Append() = new DropDownListStringItem(STR_ORDER_CONDITIONAL_LOAD_PERCENTAGE + _order_conditional_variable[i], _order_conditional_variable[i], false);
+					list->push_back(new DropDownListStringItem(STR_ORDER_CONDITIONAL_LOAD_PERCENTAGE + _order_conditional_variable[i], _order_conditional_variable[i], false));
 				}
 				ShowDropDownList(this, list, this->vehicle->GetOrder(this->OrderGetSel())->GetConditionVariable(), WID_O_COND_VARIABLE);
 				break;