--- a/tree_cmd.c	Wed Oct 19 08:34:37 2005 +0000
+++ b/tree_cmd.c	Wed Oct 19 14:49:46 2005 +0000
@@ -339,7 +339,8 @@
 }
 
 
-static uint GetSlopeZ_Trees(TileInfo *ti) {
+static uint GetSlopeZ_Trees(const TileInfo* ti)
+{
 	return GetPartialZ(ti->x & 0xF, ti->y & 0xF, ti->tileh) + ti->z;
 }