diff --git a/src/date_gui.cpp b/src/date_gui.cpp
--- a/src/date_gui.cpp
+++ b/src/date_gui.cpp
@@ -65,7 +65,7 @@ struct SetDateWindow : Window {
 	 * Helper function to construct the dropdown.
 	 * @param widget the dropdown widget to create the dropdown for
 	 */
-	void ShowDateDropDown(int widget)
+	void ShowDateDropDown(WidgetID widget)
 	{
 		int selected;
 		DropDownList list;
@@ -99,7 +99,7 @@ struct SetDateWindow : Window {
 		ShowDropDownList(this, std::move(list), selected, widget);
 	}
 
-	void UpdateWidgetSize(int widget, Dimension *size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension *fill, [[maybe_unused]] Dimension *resize) override
+	void UpdateWidgetSize(WidgetID widget, Dimension *size, [[maybe_unused]] const Dimension &padding, [[maybe_unused]] Dimension *fill, [[maybe_unused]] Dimension *resize) override
 	{
 		Dimension d = {0, 0};
 		switch (widget) {
@@ -128,7 +128,7 @@ struct SetDateWindow : Window {
 		*size = d;
 	}
 
-	void SetStringParameters(int widget) const override
+	void SetStringParameters(WidgetID widget) const override
 	{
 		switch (widget) {
 			case WID_SD_DAY:   SetDParam(0, this->date.day - 1 + STR_DAY_NUMBER_1ST); break;
@@ -137,7 +137,7 @@ struct SetDateWindow : Window {
 		}
 	}
 
-	void OnClick([[maybe_unused]] Point pt, int widget, [[maybe_unused]] int click_count) override
+	void OnClick([[maybe_unused]] Point pt, WidgetID widget, [[maybe_unused]] int click_count) override
 	{
 		switch (widget) {
 			case WID_SD_DAY:
@@ -153,7 +153,7 @@ struct SetDateWindow : Window {
 		}
 	}
 
-	void OnDropdownSelect(int widget, int index) override
+	void OnDropdownSelect(WidgetID widget, int index) override
 	{
 		switch (widget) {
 			case WID_SD_DAY: