diff --git a/src/settings_gui.cpp b/src/settings_gui.cpp
--- a/src/settings_gui.cpp
+++ b/src/settings_gui.cpp
@@ -2751,7 +2751,7 @@ struct CustomCurrencyWindow : Window {
 		this->SetWidgetDisabledState(WID_CC_RATE_DOWN, _custom_currency.rate == 1);
 		this->SetWidgetDisabledState(WID_CC_RATE_UP, _custom_currency.rate == UINT16_MAX);
 		this->SetWidgetDisabledState(WID_CC_YEAR_DOWN, _custom_currency.to_euro == CF_NOEURO);
-		this->SetWidgetDisabledState(WID_CC_YEAR_UP, _custom_currency.to_euro == MAX_YEAR);
+		this->SetWidgetDisabledState(WID_CC_YEAR_UP, _custom_currency.to_euro == CalendarTime::MAX_YEAR);
 	}
 
 	void SetStringParameters(int widget) const override
@@ -2850,8 +2850,8 @@ struct CustomCurrencyWindow : Window {
 				break;
 
 			case WID_CC_YEAR_UP:
-				_custom_currency.to_euro = Clamp(_custom_currency.to_euro + 1, MIN_EURO_YEAR, MAX_YEAR);
-				if (_custom_currency.to_euro == MAX_YEAR) this->DisableWidget(WID_CC_YEAR_UP);
+				_custom_currency.to_euro = Clamp(_custom_currency.to_euro + 1, MIN_EURO_YEAR, CalendarTime::MAX_YEAR);
+				if (_custom_currency.to_euro == CalendarTime::MAX_YEAR) this->DisableWidget(WID_CC_YEAR_UP);
 				this->EnableWidget(WID_CC_YEAR_DOWN);
 				break;
 
@@ -2897,7 +2897,7 @@ struct CustomCurrencyWindow : Window {
 			case WID_CC_YEAR: { // Year to switch to euro
 				TimerGameCalendar::Year val = atoi(str);
 
-				_custom_currency.to_euro = (val < MIN_EURO_YEAR ? CF_NOEURO : std::min(val, MAX_YEAR));
+				_custom_currency.to_euro = (val < MIN_EURO_YEAR ? CF_NOEURO : std::min(val, CalendarTime::MAX_YEAR));
 				break;
 			}
 		}