diff --git a/prjxray/grid.py b/prjxray/grid.py
index 04179e36..610bebbc 100644
--- a/prjxray/grid.py
+++ b/prjxray/grid.py
@@ -68,6 +68,7 @@ class Grid(object):
             self.tileinfo[tile] = GridInfo(
                 bits=bits,
                 sites=tileinfo['sites'],
+                prohibited_sites=tileinfo['prohibited_sites'],
                 tile_type=tileinfo['type'],
                 pin_functions=tileinfo.get('pin_functions', {}),
                 clock_region=clock_region,
diff --git a/prjxray/grid_types.py b/prjxray/grid_types.py
index a27c3ac8..75f3c74e 100644
--- a/prjxray/grid_types.py
+++ b/prjxray/grid_types.py
@@ -13,7 +13,7 @@ class BlockType(enum.Enum):
 GridLoc = namedtuple('GridLoc', 'grid_x grid_y')
 ClockRegion = namedtuple('ClockRegion', 'name x y')
 GridInfo = namedtuple(
-    'GridInfo', 'bits sites tile_type pin_functions clock_region')
+    'GridInfo', 'bits sites prohibited_sites tile_type pin_functions clock_region')
 BitAlias = namedtuple('BitAlias', 'tile_type start_offset sites')
 Bits = namedtuple('Bits', 'base_address frames offset words alias')
 BitsInfo = namedtuple('BitsInfo', 'block_type tile bits')