diff --git a/src/anndata/compat/__init__.py b/src/anndata/compat/__init__.py
index 255ffa548..55e1c2695 100644
--- a/src/anndata/compat/__init__.py
+++ b/src/anndata/compat/__init__.py
@@ -47,7 +47,7 @@ class Empty:
     pass
 
 
-Index1D = slice | int | str | np.int64 | np.ndarray
+Index1D = slice | int | str | np.int64 | np.ndarray | pd.Series[bool]
 IndexRest = Index1D | EllipsisType
 Index = (
     IndexRest
diff --git a/tests/test_concatenate.py b/tests/test_concatenate.py
index 1cc3e8b3f..3dd5a361e 100644
--- a/tests/test_concatenate.py
+++ b/tests/test_concatenate.py
@@ -1444,7 +1444,7 @@ def test_concat_outer_aligned_mapping(elem):
     del b.obsm[elem]
 
     concated = concat({"a": a, "b": b}, join="outer", label="group")
-    result = concated.obsm[elem][(concated.obs["group"] == "b").to_numpy()]
+    result = concated[concated.obs["group"] == "b"].obsm[elem]
 
     check_filled_like(result, elem_name=f"obsm/{elem}")