diff -r 84d58305a9ed nml/global_constants.py
--- a/nml/global_constants.py	Sat Feb 21 13:53:13 2015 +0100
+++ b/nml/global_constants.py	Fri Mar 20 20:35:34 2015 +0100
@@ -1060,6 +1060,7 @@
     'traffic_side'                       : {'param': 0x86, 'bit': 4},
     'desert_paved_roads'                 : {'param': 0x9E, 'bit': 1},
     'train_width_32_px'                  : {'param': 0x9E, 'bit': 3},
+    'second_rocky_tile_set'              : {'param': 0x9E, 'bit': 6},
 }
 
 def add_1920(expr, info):