diff --git a/src/spikeinterface/curation/auto_merge.py b/src/spikeinterface/curation/auto_merge.py
index 83705b94db..f2597d162f 100644
--- a/src/spikeinterface/curation/auto_merge.py
+++ b/src/spikeinterface/curation/auto_merge.py
@@ -357,8 +357,8 @@ def get_pairs_via_nntree(sorting_analyzer, k_nn=5, pair_mask=None):
 
     for unit_ind in range(n):
         mask = spikes["unit_index"] == unit_ind
-        valid = pair_mask[unit_ind, unit_ind+1:]
-        valid_indices = np.arange(unit_ind+1, n)[valid]
+        valid = pair_mask[unit_ind, unit_ind + 1 :]
+        valid_indices = np.arange(unit_ind + 1, n)[valid]
         if len(valid_indices) > 0:
             ind = kdtree.kneighbors(data[mask], return_distance=False)
             ind = ind.flatten()
@@ -366,7 +366,7 @@ def get_pairs_via_nntree(sorting_analyzer, k_nn=5, pair_mask=None):
             ind = ind[mask_2]
             chan_inds, all_counts = np.unique(spikes["unit_index"][ind], return_counts=True)
             all_counts = all_counts.astype(float)
-            #all_counts /= all_spike_counts[chan_inds]
+            # all_counts /= all_spike_counts[chan_inds]
             best_indices = np.argsort(all_counts)[::-1][0:]
             pair_mask[unit_ind] &= np.isin(np.arange(n), chan_inds[best_indices])
     return pair_mask