diff --git a/CHANGES.rst b/CHANGES.rst
index c4870485..9ec515f4 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,6 +1,16 @@
 Change Log
 ===================
 
+Unreleased
+----------
+
+Fixes:
+
+- The `test_repeated_summation_complexity` test regularly failed close to its threshold
+  despite the repeated summation complexity not being compromised. In this release, the
+  test tolerance has been relaxed to reduce the number of false failures. Fixes
+  `#343 <https://github.com/lmfit/uncertainties/issues/343>`_.
+
 3.2.4   2026-January-9
 -----------------------
 
diff --git a/tests/test_performance.py b/tests/test_performance.py
index 9f0d5eb0..da6adb05 100644
--- a/tests/test_performance.py
+++ b/tests/test_performance.py
@@ -1,4 +1,3 @@
-from math import log10
 import time
 import timeit
 
@@ -46,9 +45,8 @@ def test_repeated_summation_complexity():
     n0 = n_list[0]
     t0 = t_list[0]
     for n, t in zip(n_list[1:], t_list[1:]):
-        # Check that the plot of t vs n is linear on a log scale to within 10%
-        # See PR 275
-        assert 0.9 * log10(n / n0) < log10(t / t0) < 1.1 * log10(n / n0)
+        # Check that t vs n is sub-quadratic. See PR #275
+        assert t / t0 < (n / n0) ** 1.5
 
 
 @pytest.mark.parametrize("num", (10, 100, 1000, 10000, 100000))