diff --git a/src/economy.cpp b/src/economy.cpp
--- a/src/economy.cpp
+++ b/src/economy.cpp
@@ -29,7 +29,6 @@
 #include "newgrf_roadstop.h"
 #include "object.h"
 #include "strings_func.h"
-#include "date_func.h"
 #include "vehicle_func.h"
 #include "sound_func.h"
 #include "autoreplace_func.h"
@@ -693,7 +692,7 @@ static void CompaniesGenStatistics()
 	cur_company.Restore();
 
 	/* Only run the economic statics and update company stats every 3rd month (1st of quarter). */
-	if (!HasBit(1 << 0 | 1 << 3 | 1 << 6 | 1 << 9, _cur_month)) return;
+	if (!HasBit(1 << 0 | 1 << 3 | 1 << 6 | 1 << 9, TimerGameCalendar::month)) return;
 
 	for (Company *c : Company::Iterate()) {
 		/* Drop the oldest history off the end */
@@ -737,7 +736,7 @@ bool AddInflation(bool check_year)
 	 * inflation doesn't add anything after that either; it even makes playing
 	 * it impossible due to the diverging cost and income rates.
 	 */
-	if (check_year && (_cur_year < ORIGINAL_BASE_YEAR || _cur_year >= ORIGINAL_MAX_YEAR)) return true;
+	if (check_year && (TimerGameCalendar::year < ORIGINAL_BASE_YEAR || TimerGameCalendar::year >= ORIGINAL_MAX_YEAR)) return true;
 
 	if (_economy.inflation_prices == MAX_INFLATION || _economy.inflation_payment == MAX_INFLATION) return true;
 
@@ -846,8 +845,8 @@ static void CompaniesPayInterest()
 		if (c->money < 0) {
 			yearly_fee += -c->money *_economy.interest_rate / 100;
 		}
-		Money up_to_previous_month = yearly_fee * _cur_month / 12;
-		Money up_to_this_month = yearly_fee * (_cur_month + 1) / 12;
+		Money up_to_previous_month = yearly_fee * TimerGameCalendar::month / 12;
+		Money up_to_this_month = yearly_fee * (TimerGameCalendar::month + 1) / 12;
 
 		SubtractMoneyFromCompany(CommandCost(EXPENSES_LOAN_INTEREST, up_to_this_month - up_to_previous_month));
 
@@ -930,7 +929,7 @@ void StartupEconomy()
 
 	if (_settings_game.economy.inflation) {
 		/* Apply inflation that happened before our game start year. */
-		int months = (std::min(_cur_year, ORIGINAL_MAX_YEAR) - ORIGINAL_BASE_YEAR) * 12;
+		int months = (std::min(TimerGameCalendar::year, ORIGINAL_MAX_YEAR) - ORIGINAL_BASE_YEAR) * 12;
 		for (int i = 0; i < months; i++) {
 			AddInflation(false);
 		}
@@ -1082,7 +1081,7 @@ static uint DeliverGoodsToIndustry(const
 
 		uint amount = std::min(num_pieces, 0xFFFFu - ind->incoming_cargo_waiting[cargo_index]);
 		ind->incoming_cargo_waiting[cargo_index] += amount;
-		ind->last_cargo_accepted_at[cargo_index] = _date;
+		ind->last_cargo_accepted_at[cargo_index] = TimerGameCalendar::date;
 		num_pieces -= amount;
 		accepted += amount;
 
@@ -1778,7 +1777,7 @@ static void LoadUnloadVehicle(Vehicle *f
 
 		/* if last speed is 0, we treat that as if no vehicle has ever visited the station. */
 		ge->last_speed = std::min(t, 255);
-		ge->last_age = std::min(_cur_year - front->build_year, 255);
+		ge->last_age = std::min(TimerGameCalendar::year - front->build_year, 255);
 
 		assert(v->cargo_cap >= v->cargo.StoredCount());
 		/* Capacity available for loading more cargo. */
@@ -2048,7 +2047,7 @@ CommandCost CmdBuyShareInCompany(DoComma
 	if (c == nullptr || !_settings_game.economy.allow_shares || _current_company == target_company) return CMD_ERROR;
 
 	/* Protect new companies from hostile takeovers */
-	if (_cur_year - c->inaugurated_year < _settings_game.economy.min_years_for_shares) return_cmd_error(STR_ERROR_PROTECTED);
+	if (TimerGameCalendar::year - c->inaugurated_year < _settings_game.economy.min_years_for_shares) return_cmd_error(STR_ERROR_PROTECTED);
 
 	/* Those lines are here for network-protection (clients can be slow) */
 	if (GetAmountOwnedBy(c, INVALID_OWNER) == 0) return cost;