diff --git a/python/python/lancedb/util.py b/python/python/lancedb/util.py
index 932a3e982..6a5be99db 100644
--- a/python/python/lancedb/util.py
+++ b/python/python/lancedb/util.py
@@ -177,7 +177,10 @@ def flatten_columns(tbl: pa.Table, flatten: Optional[Union[int, bool]] = None):
                 continue
             else:
                 break
-    elif isinstance(flatten, int):
+    # `bool` is a subclass of `int`, so guard against it explicitly: `flatten=False`
+    # (and `None`) must mean "do not flatten" rather than falling into the integer
+    # branch and raising on the `flatten <= 0` check.
+    elif isinstance(flatten, int) and not isinstance(flatten, bool):
         if flatten <= 0:
             raise ValueError(
                 "Please specify a positive integer for flatten or the boolean "
diff --git a/python/python/tests/test_util.py b/python/python/tests/test_util.py
index c96407779..da33cc77f 100644
--- a/python/python/tests/test_util.py
+++ b/python/python/tests/test_util.py
@@ -25,10 +25,42 @@ import pandas as pd
 import polars as pl
 import pytest
 import lancedb
-from lancedb.util import get_uri_scheme, join_uri, value_to_sql
+from lancedb.util import flatten_columns, get_uri_scheme, join_uri, value_to_sql
 from utils import exception_output
 
 
+def _struct_table() -> pa.Table:
+    return pa.table(
+        {
+            "id": [1, 2],
+            "nested": pa.array([{"a": 1, "b": 2}, {"a": 3, "b": 4}]),
+        }
+    )
+
+
+def test_flatten_columns():
+    tbl = _struct_table()
+
+    # None / False mean "do not flatten": the struct column is preserved.
+    # `False` is a regression guard: because bool is a subclass of int it used
+    # to fall into the integer branch and raise ValueError (see issue).
+    for no_flatten in (None, False):
+        result = flatten_columns(tbl, no_flatten)
+        assert result.column_names == ["id", "nested"]
+
+    # True flattens all nested levels.
+    flattened = flatten_columns(tbl, True)
+    assert flattened.column_names == ["id", "nested.a", "nested.b"]
+
+    # A positive integer flattens up to that depth.
+    flattened = flatten_columns(tbl, 1)
+    assert flattened.column_names == ["id", "nested.a", "nested.b"]
+
+    # Non-positive integers are still rejected.
+    with pytest.raises(ValueError):
+        flatten_columns(tbl, 0)
+
+
 def test_normalize_uri():
     uris = [
         "relative/path",