diff --git a/src/opticalattackdetector/tests/test_unitary.py b/src/opticalattackdetector/tests/test_unitary.py
index c1db52f03c0299e8d037bb3d920b711d57a8b463..139e898907a3f5819e54eff78f78a41cc8062167 100644
--- a/src/opticalattackdetector/tests/test_unitary.py
+++ b/src/opticalattackdetector/tests/test_unitary.py
@@ -55,7 +55,7 @@ def test_detect_attack(
     optical_attack_detector_client: OpticalAttackDetectorClient,
 ):
     message = dbscan.DetectionResponse()
-    message.cluster_indices.extend([0, 1, -1, -1, -1])
+    message.cluster_indices.extend([0, 1] * 5 + [-1] * 10)
 
     with patch(
         "opticalattackdetector.service.OpticalAttackDetectorServiceServicerImpl.attack_mitigator_client"