diff --git a/marimo/_config/reader.py b/marimo/_config/reader.py
index c2acc9ca36b..1fb6a66e68e 100644
--- a/marimo/_config/reader.py
+++ b/marimo/_config/reader.py
@@ -52,10 +52,13 @@ def find_nearest_pyproject_toml(
     """Find the nearest pyproject.toml file."""
     path = Path(start_path)
     root = path.anchor
-    while not path.joinpath("pyproject.toml").exists():
-        if str(path) == root:
-            return None
-        if path.parent == path:
-            return None
-        path = path.parent
+    try:
+        while not path.joinpath("pyproject.toml").exists():
+            if str(path) == root:
+                return None
+            if path.parent == path:
+                return None
+            path = path.parent
+    except OSError:
+        return None
     return path.joinpath("pyproject.toml")
diff --git a/tests/_config/test_reader.py b/tests/_config/test_reader.py
index f88c7bb144c..8b8e2af4624 100644
--- a/tests/_config/test_reader.py
+++ b/tests/_config/test_reader.py
@@ -111,7 +111,7 @@ def test_read_pyproject_config_no_file(tmp_path: Path):
     assert nearest_pyproject_toml is None
 
 
-def testfind_nearest_pyproject_toml():
+def test_find_nearest_pyproject_toml():
     with tempfile.TemporaryDirectory() as temp_dir:
         parent_dir = os.path.join(temp_dir, "parent")
         os.makedirs(parent_dir)
@@ -125,12 +125,19 @@ def testfind_nearest_pyproject_toml():
         assert result == Path(pyproject_path)
 
 
-def testfind_nearest_pyproject_toml_not_found():
+def test_find_nearest_pyproject_toml_not_found():
     with tempfile.TemporaryDirectory() as temp_dir:
         result = find_nearest_pyproject_toml(temp_dir)
         assert result is None
 
 
+def test_find_nearest_pyproject_toml_permission_error():
+    with patch("pathlib.Path.exists") as mock_exists:
+        mock_exists.side_effect = PermissionError("Permission denied")
+        result = find_nearest_pyproject_toml("/some/path")
+        assert result is None
+
+
 def test_read_toml_invalid_content():
     invalid_toml = b"""
     [invalid