diff --git a/src/ai/moves/height.py b/src/ai/moves/height.py
index cb331c4..8f87b05 100644
--- a/src/ai/moves/height.py
+++ b/src/ai/moves/height.py
@@ -1,9 +1,7 @@
-from typing import Any
-
 import numpy as np
 
 
-def aggregate_height(field: np.ndarray[int, Any]) -> int:
+def aggregate_height(field: np.ndarray[int, np.dtype[np.uint8]]) -> int:
     """
     Calculates the aggregate height of the field.
 
@@ -13,4 +11,4 @@ def aggregate_height(field: np.ndarray[int, Any]) -> int:
     Returns:
         The aggregate height of the field.
     """
-    return np.sum(field.shape[0] - np.argmax(field, axis=0))
+    return int(np.sum(field.shape[0] - np.argmax(field, axis=0)))
diff --git a/src/ai/moves/holes.py b/src/ai/moves/holes.py
new file mode 100644
index 0000000..1479ed5
--- /dev/null
+++ b/src/ai/moves/holes.py
@@ -0,0 +1,26 @@
+from typing import Optional
+
+import numpy as np
+
+
+def holes(
+    field: np.ndarray[int, np.dtype[np.uint8]],
+) -> int:
+    """
+    Calculate the number of holes in each column of the given field.
+
+    Args:
+        field: The signal field.
+        peaks: Array containing peak indices. If not provided, it will be computed from the field.
+
+    Returns:
+        The total number of holes in the field.
+    """
+
+    first_nonzero_indices = np.argmax(field != 0, axis=0)
+
+    mask = (field == 0) & (
+        np.arange(field.shape[0])[:, np.newaxis] > first_nonzero_indices
+    )
+
+    return int(np.sum(mask))
diff --git a/src/ai/moves/lines.py b/src/ai/moves/lines.py
index 324d7ad..01d9061 100644
--- a/src/ai/moves/lines.py
+++ b/src/ai/moves/lines.py
@@ -1,9 +1,7 @@
-from typing import Any
-
 import numpy as np
 
 
-def complete_lines(field: np.ndarray[int, Any]) -> int:
+def complete_lines(field: np.ndarray[int, np.dtype[np.uint8]]) -> int:
     """
     Calculates the number of complete lines in the field.
 
@@ -13,4 +11,4 @@ def complete_lines(field: np.ndarray[int, Any]) -> int:
     Returns:
         The number of complete lines in the field.
     """
-    return np.sum(np.all(field, axis=1))
+    return int(np.sum(np.all(field, axis=1)))
diff --git a/tests/ai/test_moves.py b/tests/ai/test_moves.py
index e8194f1..de9c0a6 100644
--- a/tests/ai/test_moves.py
+++ b/tests/ai/test_moves.py
@@ -2,6 +2,7 @@ import unittest
 
 import numpy as np
 from ai.moves.height import aggregate_height
+from ai.moves.holes import holes
 from ai.moves.lines import complete_lines
 
 
@@ -23,3 +24,6 @@ class TestFitness(unittest.TestCase):
 
     def test_complete_lines(self) -> None:
         self.assertEqual(complete_lines(self.field), 2)
+
+    def test_holes(self) -> None:
+        self.assertEqual(holes(self.field), 2)