diff --git a/sdmetrics/column_pairs/statistical/statistic_msas.py b/sdmetrics/column_pairs/statistical/statistic_msas.py
index 8afab764..8440618d 100644
--- a/sdmetrics/column_pairs/statistical/statistic_msas.py
+++ b/sdmetrics/column_pairs/statistical/statistic_msas.py
@@ -1,6 +1,5 @@
 """StatisticMSAS module."""
 
-import numpy as np
 import pandas as pd
 
 from sdmetrics.goal import Goal
@@ -61,18 +60,9 @@ def compute(real_data, synthetic_data, statistic='mean'):
             float:
                 The similarity score between the real and synthetic data distributions.
         """
-        statistic_functions = {
-            'mean': np.mean,
-            'median': np.median,
-            'std': np.std,
-            'min': np.min,
-            'max': np.max,
-        }
-        if statistic not in statistic_functions:
-            raise ValueError(
-                f'Invalid statistic: {statistic}.'
-                f' Choose from [{", ".join(statistic_functions.keys())}].'
-            )
+        valid_statistics = ['mean', 'median', 'std', 'min', 'max']
+        if statistic not in valid_statistics:
+            raise ValueError(f'Invalid statistic: {statistic}. Choose from {valid_statistics}.')
 
         for data in [real_data, synthetic_data]:
             if (
@@ -84,11 +74,10 @@ def compute(real_data, synthetic_data, statistic='mean'):
 
         real_keys, real_values = real_data
         synthetic_keys, synthetic_values = synthetic_data
-        stat_func = statistic_functions[statistic]
 
         def calculate_statistics(keys, values):
             df = pd.DataFrame({'keys': keys, 'values': values})
-            return df.groupby('keys')['values'].agg(stat_func)
+            return df.groupby('keys')['values'].agg(statistic)
 
         real_stats = calculate_statistics(real_keys, real_values)
         synthetic_stats = calculate_statistics(synthetic_keys, synthetic_values)
diff --git a/tests/unit/column_pairs/statistical/test_statistic_msas.py b/tests/unit/column_pairs/statistical/test_statistic_msas.py
index 9e8813eb..52338844 100644
--- a/tests/unit/column_pairs/statistical/test_statistic_msas.py
+++ b/tests/unit/column_pairs/statistical/test_statistic_msas.py
@@ -7,7 +7,7 @@
 
 
 class TestStatisticMSAS:
-    def test_compute_identical_sequences(self):
+    def test_compute_identical_sequences(self, recwarn):
         """Test it returns 1 when real and synthetic data are identical."""
         # Setup
         real_keys = pd.Series(['id1', 'id1', 'id1', 'id2', 'id2', 'id2'])
@@ -24,6 +24,9 @@ def test_compute_identical_sequences(self):
             )
             assert score == 1
 
+        # Ensure GH#665 is fixed
+        assert len(recwarn) == 0
+
     def test_compute_different_sequences(self):
         """Test it for distinct distributions."""
         # Setup
@@ -87,7 +90,7 @@ def test_compute_with_invalid_statistic(self):
 
         # Run and Assert
         err_msg = re.escape(
-            'Invalid statistic: invalid. Choose from [mean, median, std, min, max].'
+            "Invalid statistic: invalid. Choose from ['mean', 'median', 'std', 'min', 'max']."
         )
         with pytest.raises(ValueError, match=err_msg):
             StatisticMSAS.compute(