diff --git a/packages/essreduce/src/ess/reduce/live/raw.py b/packages/essreduce/src/ess/reduce/live/raw.py
index 48197886d..36095a439 100644
--- a/packages/essreduce/src/ess/reduce/live/raw.py
+++ b/packages/essreduce/src/ess/reduce/live/raw.py
@@ -739,7 +739,7 @@ def position_noise_for_cylindrical_pixel(
     # fulfill this. However, the rest of the data reduction currently assumes that
     # the pixel offset corresponds to the pixel center, so if it is not fulfilled
     # there are bigger problems elsewhere anywhere.
-    rng = np.random.default_rng()
+    rng = np.random.default_rng(seed=1234)
     dims = ('position',)
     size = _noise_size
     z_hat = axis / sc.norm(axis)  # Unit vector along the cylinder axis
diff --git a/packages/essreduce/tests/live/raw_test.py b/packages/essreduce/tests/live/raw_test.py
index e82f072fd..95f8f87ff 100644
--- a/packages/essreduce/tests/live/raw_test.py
+++ b/packages/essreduce/tests/live/raw_test.py
@@ -19,6 +19,14 @@ def test_gaussian_position_noise_is_sigma_unit_independent(sigma: sc.Variable) -
     assert sc.identical(noise, reference)
 
 
+def test_position_noise_for_cylindrical_pixel_is_deterministic() -> None:
+    axis = raw.PixelCylinderAxis(sc.vector([0.0, 0.0, 1.0], unit='m'))
+    radius = raw.PixelCylinderRadius(sc.vector([0.5, 0.0, 0.0], unit='m'))
+    reference = raw.position_noise_for_cylindrical_pixel(axis=axis, radius=radius)
+    noise = raw.position_noise_for_cylindrical_pixel(axis=axis, radius=radius)
+    assert sc.identical(noise, reference)
+
+
 def test_clear_counts_resets_counts_to_zero() -> None:
     detector_number = sc.array(dims=['pixel'], values=[1, 2, 3], unit=None)
     det = raw.Detector(detector_number)