diff --git a/src/spikeinterface/qualitymetrics/tests/test_quality_metric_calculator.py b/src/spikeinterface/qualitymetrics/tests/test_quality_metric_calculator.py
index 56e3975210..71569e7b2b 100644
--- a/src/spikeinterface/qualitymetrics/tests/test_quality_metric_calculator.py
+++ b/src/spikeinterface/qualitymetrics/tests/test_quality_metric_calculator.py
@@ -136,12 +136,12 @@ def test_empty_units(sorting_analyzer_simple):
     # num_spikes are ints not nans so we confirm empty units are nans for everything except
     # num_spikes which should be 0
     nan_containing_columns = [column for column in metrics_empty.columns if column != "num_spikes"]
-    for empty_unit_id in sorting_empty.get_empty_unit_ids():
+    for empty_unit_ids in sorting_empty.get_empty_unit_ids():
         from pandas import isnull
 
-        assert np.all(isnull(metrics_empty.loc[empty_unit_id, nan_containing_columns].values))
+        assert np.all(isnull(metrics_empty.loc[empty_unit_ids, nan_containing_columns].values))
         if "num_spikes" in metrics_empty.columns:
-            assert metrics_empty.loc[empty_unit_id, ["num_spikes"]] == 0
+            assert sum(metrics_empty.loc[empty_unit_ids, ["num_spikes"]]) == 0
 
 
 # TODO @alessio all theses old test should be moved in test_metric_functions.py or test_pca_metrics()