diff --git a/python/gtsam/tests/test_ShonanAveraging.py b/python/gtsam/tests/test_ShonanAveraging.py
index 19b9f8dc1a..9636698972 100644
--- a/python/gtsam/tests/test_ShonanAveraging.py
+++ b/python/gtsam/tests/test_ShonanAveraging.py
@@ -197,9 +197,8 @@ def test_constructorBetweenFactorPose2s(self) -> None:
         wRi_list = [result_values.atRot2(i) for i in range(num_images)]
         thetas_deg = np.array([wRi.degrees() for wRi in wRi_list])
         
-        # map all angles to [0,360)
-        thetas_deg = thetas_deg % 360
-        thetas_deg -= thetas_deg[0]
+        # map all angles to [-180,180)
+        thetas_deg = (thetas_deg - thetas_deg[0] + 180) % 360 - 180
         
         expected_thetas_deg = np.array([0.0, 90.0, 0.0])
         np.testing.assert_allclose(thetas_deg, expected_thetas_deg, atol=0.1)