diff --git a/src/newgrf_station.cpp b/src/newgrf_station.cpp
--- a/src/newgrf_station.cpp
+++ b/src/newgrf_station.cpp
@@ -291,7 +291,7 @@ TownScopeResolver *StationResolverObject
 				}
 				break;
 
-			case 0xFA: return ClampTo<uint16_t>(TimerGameCalendar::date - DAYS_TILL_ORIGINAL_BASE_YEAR); // Build date, clamped to a 16 bit value
+			case 0xFA: return ClampTo<uint16_t>(TimerGameCalendar::date - CalendarTime::DAYS_TILL_ORIGINAL_BASE_YEAR); // Build date, clamped to a 16 bit value
 		}
 
 		*available = false;
@@ -381,7 +381,7 @@ TownScopeResolver *StationResolverObject
 		case 0x84: return this->st->string_id;
 		case 0x86: return 0;
 		case 0xF0: return this->st->facilities;
-		case 0xFA: return ClampTo<uint16_t>(this->st->build_date - DAYS_TILL_ORIGINAL_BASE_YEAR);
+		case 0xFA: return ClampTo<uint16_t>(this->st->build_date - CalendarTime::DAYS_TILL_ORIGINAL_BASE_YEAR);
 	}
 
 	return this->st->GetNewGRFVariable(this->ro, variable, parameter, available);