diff --git a/src/toolbar_gui.cpp b/src/toolbar_gui.cpp
--- a/src/toolbar_gui.cpp
+++ b/src/toolbar_gui.cpp
@@ -17,8 +17,6 @@
 #include "rail_gui.h"
 #include "road.h"
 #include "road_gui.h"
-#include "date_func.h"
-#include "timer/timer_game_calendar.h"
 #include "vehicle_func.h"
 #include "sound_func.h"
 #include "terraform_gui.h"
@@ -56,6 +54,7 @@
 #include "league_base.h"
 #include "timer/timer.h"
 #include "timer/timer_window.h"
+#include "timer/timer_game_calendar.h"
 
 #include "widgets/toolbar_widget.h"
 
@@ -1148,7 +1147,7 @@ void ToggleDirtyBlocks()
 void SetStartingYear(TimerGameCalendar::Year year)
 {
 	_settings_game.game_creation.starting_year = Clamp(year, MIN_YEAR, MAX_YEAR);
-	TimerGameCalendar::Date new_date = ConvertYMDToDate(_settings_game.game_creation.starting_year, 0, 1);
+	TimerGameCalendar::Date new_date = TimerGameCalendar::ConvertYMDToDate(_settings_game.game_creation.starting_year, 0, 1);
 	/* If you open a savegame as scenario there may already be link graphs.*/
 	LinkGraphSchedule::instance.ShiftDates(new_date - TimerGameCalendar::date);
 	TimerGameCalendar::SetDate(new_date, 0);
@@ -2377,7 +2376,7 @@ struct ScenarioEditorToolbarWindow : Win
 	{
 		switch (widget) {
 			case WID_TE_DATE:
-				SetDParam(0, ConvertYMDToDate(_settings_game.game_creation.starting_year, 0, 1));
+				SetDParam(0, TimerGameCalendar::ConvertYMDToDate(_settings_game.game_creation.starting_year, 0, 1));
 				break;
 		}
 	}
@@ -2406,7 +2405,7 @@ struct ScenarioEditorToolbarWindow : Win
 				break;
 
 			case WID_TE_DATE:
-				SetDParam(0, ConvertYMDToDate(MAX_YEAR, 0, 1));
+				SetDParam(0, TimerGameCalendar::ConvertYMDToDate(MAX_YEAR, 0, 1));
 				*size = GetStringBoundingBox(STR_WHITE_DATE_LONG);
 				break;
 		}