Index: src/tree_cmd.cpp
===================================================================
--- src/tree_cmd.cpp	(Revision 20902)
+++ src/tree_cmd.cpp	(Arbeitskopie)
@@ -493,7 +493,7 @@
 	}
 
 	/* draw them in a sorted way */
-	byte z = ti->z + GetSlopeMaxZ(ti->tileh) / 2;
+	int32 z = ti->z + GetSlopeMaxZ(ti->tileh) / 2;
 
 	for (; trees > 0; trees--) {
 		uint min = te[0].x + te[0].y;