diff --git a/muon/_core/preproc.py b/muon/_core/preproc.py
index a24b788..e91d8e4 100644
--- a/muon/_core/preproc.py
+++ b/muon/_core/preproc.py
@@ -29,7 +29,11 @@
 from packaging.version import Version
 
 if Version(scanpy.__version__) < Version("1.10"):
-    from scanpy.neighbors import _compute_connectivities_umap
+    from scanpy.neighbors import _compute_connectivities_umap as __compute_connectivities_umap
+
+    _compute_connectivities_umap = lambda *args, **kwargs: __compute_connectivities_umap(
+        *args, **kwargs
+    )[1]
 else:
     from scanpy.neighbors._connectivity import umap as _compute_connectivities_umap
 
@@ -520,7 +524,7 @@ def neighbors(
             (
                 distances[:, 1:].reshape(-1),
                 nn_indices[:, 1:].reshape(-1),
-                np.concatenate((nn_indices[:, 0] * n_multineighbors, (nn_indices[:, 1:].size,))),
+                np.arange((nn_indices.shape[0] + 1) * n_multineighbors, step=n_multineighbors),
             ),
             shape=(rep.shape[0], rep.shape[0]),
         )