diff --git a/tools/grid.py b/tools/grid.py
index 6c5b53a..50190da 100644
--- a/tools/grid.py
+++ b/tools/grid.py
@@ -377,8 +377,8 @@ class Grid:
         )
 
     @classmethod
-    def from_str(cls, grid_string: str, true_char: str = '#') -> 'Grid':
-        ret = cls()
+    def from_str(cls, grid_string: str, true_char: str = '#', default: Any = False) -> 'Grid':
+        ret = cls(default=default)
         for y, line in enumerate(grid_string.split("/")):
             for x, c in enumerate(line):
                 ret.set(Coordinate(x, y), c == true_char)