diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp
--- a/src/town_cmd.cpp
+++ b/src/town_cmd.cpp
@@ -873,7 +873,7 @@ RoadType GetTownRoadType(const Town *t)
 		if (!HasBit(rti->flags, ROTF_TOWN_BUILD)) continue;
 
 		/* Not yet introduced at this date. */
-		if (IsInsideMM(rti->introduction_date, 0, MAX_DAY) && rti->introduction_date > TimerGameCalendar::date) continue;
+		if (IsInsideMM(rti->introduction_date, 0, MAX_DATE) && rti->introduction_date > TimerGameCalendar::date) continue;
 
 		if (best != nullptr) {
 			if ((rti->max_speed == 0 ? assume_max_speed : rti->max_speed) < (best->max_speed == 0 ? assume_max_speed : best->max_speed)) continue;