--- a/vehicle.c	Sun Jul 17 20:09:02 2005 +0000
+++ b/vehicle.c	Sun Jul 17 20:14:58 2005 +0000
@@ -1214,7 +1214,7 @@
 	_effect_tick_procs[v->subtype](v);
 }
 
-Vehicle *CheckClickOnVehicle(ViewPort *vp, int x, int y)
+Vehicle *CheckClickOnVehicle(const ViewPort *vp, int x, int y)
 {
 	Vehicle *found = NULL, *v;
 	uint dist, best_dist = (uint)-1;