diff --git a/src/newgrf_station.cpp b/src/newgrf_station.cpp
--- a/src/newgrf_station.cpp
+++ b/src/newgrf_station.cpp
@@ -523,13 +523,13 @@ uint32 Waypoint::GetNewGRFVariable(const
 	cargo = std::min(0xfffu, cargo);
 
 	if (cargo > this->station_scope.statspec->cargo_threshold) {
-		if (group->num_loading > 0) {
-			uint set = ((cargo - this->station_scope.statspec->cargo_threshold) * group->num_loading) / (4096 - this->station_scope.statspec->cargo_threshold);
+		if (!group->loading.empty()) {
+			uint set = ((cargo - this->station_scope.statspec->cargo_threshold) * (uint)group->loading.size()) / (4096 - this->station_scope.statspec->cargo_threshold);
 			return group->loading[set];
 		}
 	} else {
-		if (group->num_loaded > 0) {
-			uint set = (cargo * group->num_loaded) / (this->station_scope.statspec->cargo_threshold + 1);
+		if (!group->loaded.empty()) {
+			uint set = (cargo * (uint)group->loaded.size()) / (this->station_scope.statspec->cargo_threshold + 1);
 			return group->loaded[set];
 		}
 	}