diff --git a/python/scripts/nvbench_compare.py b/python/scripts/nvbench_compare.py
index cd17207..e601b86 100644
--- a/python/scripts/nvbench_compare.py
+++ b/python/scripts/nvbench_compare.py
@@ -1239,13 +1239,21 @@ def compute_timing_interval_from_samples(samples):
     return interval
 
 
+def percentile_rank(percentile: int, sample_count: int) -> int:
+    clamped_percentile = min(max(percentile, 0), 100)
+    return round((clamped_percentile / 100.0) * (sample_count - 1))
+
+
 def compute_robust_timing_input_from_samples(samples):
     values = positive_finite_array(samples)
     if values is None:
         return None
-    first_quartile, median, third_quartile = np.quantile(values, [0.25, 0.5, 0.75])
+    sorted_values = np.sort(values)
+    first_quartile = sorted_values[percentile_rank(25, len(sorted_values))]
+    median = sorted_values[percentile_rank(50, len(sorted_values))]
+    third_quartile = sorted_values[percentile_rank(75, len(sorted_values))]
     interval = make_timing_interval(
-        lower=np.min(values),
+        lower=sorted_values[0],
         upper=third_quartile,
         center=median,
     )
diff --git a/python/test/test_nvbench_compare.py b/python/test/test_nvbench_compare.py
index 94fcca2..75e05ed 100644
--- a/python/test/test_nvbench_compare.py
+++ b/python/test/test_nvbench_compare.py
@@ -801,14 +801,15 @@ def test_compare_gpu_timings_classifies_common_cases(tmp_path, nvbench_compare):
             mean=100.0,
             stdev=1.0,
             stdev_relative=0.01,
-            sample_values=[4.0, 5.0, 6.0],
+            sample_values=[4.0, 5.0, 6.0, 100.0],
         ),
     )
     assert mixed_robust_summary_and_bulk is not None
     assert mixed_robust_summary_and_bulk.ref_time == pytest.approx(10.0)
-    assert mixed_robust_summary_and_bulk.cmp_time == pytest.approx(5.0)
+    assert mixed_robust_summary_and_bulk.cmp_time == pytest.approx(6.0)
     assert mixed_robust_summary_and_bulk.ref_interval.center == pytest.approx(10.0)
-    assert mixed_robust_summary_and_bulk.cmp_interval.center == pytest.approx(5.0)
+    assert mixed_robust_summary_and_bulk.cmp_interval.center == pytest.approx(6.0)
+    assert mixed_robust_summary_and_bulk.cmp_interval.upper == pytest.approx(6.0)
 
     ref_interval_timing = make_gpu_timing_data(
         nvbench_compare,