diff --git a/erynrl/map/grid.py b/erynrl/map/grid.py
index b86f8af..4e495d5 100644
--- a/erynrl/map/grid.py
+++ b/erynrl/map/grid.py
@@ -1,10 +1,15 @@
 # Eryn Wells <eryn@erynwells.me>
 
+'''
+Utilities for maps.
+'''
+
 import numpy as np
 
 from .tile import Empty
 from ..geometry import Size
 
 
-def make_grid(size: Size):
-    return np.full(size.numpy_shape, fill_value=Empty, order='F')
+def make_grid(size: Size, fill: np.ndarray = Empty) -> np.ndarray:
+    '''Make a numpy array of the given size filled with `fill` tiles.'''
+    return np.full(size.numpy_shape, fill_value=fill, order='F')