diff --git a/src/script/api/script_window.cpp b/src/script/api/script_window.cpp
index a164d1f171..42b5614c03 100644
--- a/src/script/api/script_window.cpp
+++ b/src/script/api/script_window.cpp
@@ -15,7 +15,7 @@
 
 #include "../../safeguards.h"
 
-/* static */ void ScriptWindow::Close(WindowClass window, uint32 number)
+/* static */ void ScriptWindow::Close(WindowClass window, SQInteger number)
 {
 	if (ScriptGame::IsMultiplayer()) return;
 
@@ -24,10 +24,12 @@
 		return;
 	}
 
+	number = Clamp<SQInteger>(number, 0, INT32_MAX);
+
 	CloseWindowById((::WindowClass)window, number);
 }
 
-/* static */ bool ScriptWindow::IsOpen(WindowClass window, uint32 number)
+/* static */ bool ScriptWindow::IsOpen(WindowClass window, SQInteger number)
 {
 	if (ScriptGame::IsMultiplayer()) return false;
 
@@ -35,16 +37,20 @@
 		return (FindWindowByClass((::WindowClass)window) != nullptr);
 	}
 
+	number = Clamp<SQInteger>(number, 0, INT32_MAX);
+
 	return FindWindowById((::WindowClass)window, number) != nullptr;
 }
 
-/* static */ void ScriptWindow::Highlight(WindowClass window, uint32 number, uint8 widget, TextColour colour)
+/* static */ void ScriptWindow::Highlight(WindowClass window, SQInteger number, SQInteger widget, TextColour colour)
 {
 	if (ScriptGame::IsMultiplayer()) return;
 	if (number == NUMBER_ALL) return;
 	if (!IsOpen(window, number)) return;
 	if (colour != TC_INVALID && (::TextColour)colour >= ::TC_END) return;
 
+	number = Clamp<SQInteger>(number, 0, INT32_MAX);
+
 	Window *w = FindWindowById((::WindowClass)window, number);
 	assert(w != nullptr);
 
@@ -54,6 +60,8 @@
 		return;
 	}
 
+	widget = Clamp<SQInteger>(widget, 0, UINT8_MAX);
+
 	const NWidgetBase *wid = w->GetWidget<NWidgetBase>(widget);
 	if (wid == nullptr) return;
 	w->SetWidgetHighlight(widget, (::TextColour)colour);
diff --git a/src/script/api/script_window.hpp.in b/src/script/api/script_window.hpp.in
index c0f37d1070..65356b48eb 100644
--- a/src/script/api/script_window.hpp.in
+++ b/src/script/api/script_window.hpp.in
@@ -15,7 +15,7 @@
 ${INCLUDES}
 
 /**
- * Class that handles window interaction. A Window in OpenTTD has two imporant
+ * Class that handles window interaction. A Window in OpenTTD has two important
  *  values. The WindowClass, and a Window number. The first indicates roughly
  *  which window it is. WC_TOWN_VIEW for example, is the view of a town.
  * The Window number is a bit more complex, as it depends mostly on the
@@ -67,45 +67,49 @@ public:
 	 * Special number values.
 	 */
 	enum NumberType {
-		NUMBER_ALL = 0xFFFFFFFF, ///< Value to select all windows of a class.
+		NUMBER_ALL = -1, ///< Value to select all windows of a class.
 	};
 
 	/**
 	 * Special widget values.
 	 */
 	enum WidgetType {
-		WIDGET_ALL = 0xFF, ///< Value to select all widgets of a window.
+		WIDGET_ALL = -1, ///< Value to select all widgets of a window.
 	};
 
 	/**
 	 * Close a window.
 	 * @param window The class of the window to close.
 	 * @param number The number of the window to close, or NUMBER_ALL to close all of this class.
+	 *               The value will be clamped to 0 .. MAX(int32) when value is not NUMBER_ALL.
 	 * @pre !ScriptGame::IsMultiplayer().
 	 */
-	static void Close(WindowClass window, uint32 number);
+	static void Close(WindowClass window, SQInteger number);
 
 	/**
 	 * Check if a window is open.
 	 * @param window The class of the window to check for.
 	 * @param number The number of the window to check for, or NUMBER_ALL to check for any in the class.
+	 *               The value will be clamped to 0 .. MAX(int32) when value is not NUMBER_ALL.
 	 * @pre !ScriptGame::IsMultiplayer().
 	 * @return True if the window is open.
 	 */
-	static bool IsOpen(WindowClass window, uint32 number);
+	static bool IsOpen(WindowClass window, SQInteger number);
 
 	/**
 	 * Highlight a widget in a window.
 	 * @param window The class of the window to highlight a widget in.
 	 * @param number The number of the window to highlight a widget in.
+	 *               The value will be clamped to 0 .. MAX(int32) when value is not NUMBER_ALL.
 	 * @param widget The widget in the window to highlight, or WIDGET_ALL (in combination with TC_INVALID) to disable all widget highlighting on this window.
+	 *               The value will be clamped to 0 .. MAX(uint8) when value is not WIDGET_ALL.
 	 * @param colour The colour of the highlight, or TC_INVALID for disabling.
 	 * @pre !ScriptGame::IsMultiplayer().
 	 * @pre number != NUMBER_ALL.
 	 * @pre colour < TC_END || (widget == WIDGET_ALL && colour == TC_INVALID).
 	 * @pre IsOpen(window, number).
 	 */
-	static void Highlight(WindowClass window, uint32 number, uint8 widget, TextColour colour);
+	static void Highlight(WindowClass window, SQInteger number, SQInteger widget, TextColour colour);
 
 	// @enum .*Widgets ../../widgets/*_widget.h@ENUM_WIDGETS@
 	// @endenum