diff --git a/main_gui.c b/main_gui.c
index 8009f28e87..8796189538 100644
--- a/main_gui.c
+++ b/main_gui.c
@@ -888,11 +888,6 @@ bool DoZoomInOutWindow(int how, Window *w)
 	return true;
 }
 
-static void MaxZoomIn(void)
-{
-	while (DoZoomInOutWindow(ZOOM_IN, FindWindowById(WC_MAIN_WINDOW, 0) ) ) {}
-}
-
 static void ToolbarZoomInClick(Window *w)
 {
 	if (DoZoomInOutWindow(ZOOM_IN, FindWindowById(WC_MAIN_WINDOW, 0))) {
@@ -2272,7 +2267,7 @@ static void MainWindowWndProc(Window *w, WindowEvent *e)
 				Point pt = GetTileBelowCursor();
 				if (pt.x != -1) {
 					ScrollMainWindowTo(pt.x, pt.y);
-					if (e->we.keypress.keycode == 'Z') MaxZoomIn();
+					if (e->we.keypress.keycode == 'Z') MaxZoomInOut(ZOOM_IN, w);
 				}
 				break;
 			}
diff --git a/viewport.h b/viewport.h
index 9cdcdc3d5b..018a1693d8 100644
--- a/viewport.h
+++ b/viewport.h
@@ -33,6 +33,11 @@ void ZoomInOrOutToCursorWindow(bool in, Window * w);
 Point GetTileZoomCenterWindow(bool in, Window * w);
 void HandleZoomMessage(Window *w, const ViewPort *vp, byte widget_zoom_in, byte widget_zoom_out);
 
+static inline void MaxZoomInOut(int how, Window *w)
+{
+	while (DoZoomInOutWindow(how, w) ) {};
+}
+
 void OffsetGroundSprite(int x, int y);
 
 void DrawGroundSprite(uint32 image);