--- a/screenshot.c	Sat Sep 02 20:09:16 2006 +0000
+++ b/screenshot.c	Sat Sep 02 20:34:04 2006 +0000
@@ -460,7 +460,7 @@
 // generate a large piece of the world
 static void LargeWorldCallback(void *userdata, Pixel *buf, uint y, uint pitch, uint n)
 {
-	ViewPort *vp = (ViewPort *)userdata;
+	const ViewPort* vp = (const ViewPort*)userdata;
 	DrawPixelInfo dpi, *old_dpi;
 	int wx, left;