diff --git a/tests/models/gemma3n/test_feature_extraction_gemma3n.py b/tests/models/gemma3n/test_feature_extraction_gemma3n.py
index 29dba741c3da..30d2e1bb9468 100644
--- a/tests/models/gemma3n/test_feature_extraction_gemma3n.py
+++ b/tests/models/gemma3n/test_feature_extraction_gemma3n.py
@@ -277,10 +277,12 @@ def test_dither(self):
         diff = input_features_dither - input_features_no_dither
 
         # features are not identical
-        self.assertTrue(np.abs(diff).mean() > 1e-6)
+        assert np.abs(diff).mean() > 1e-6
         # features are not too different
-        self.assertTrue(np.abs(diff).mean() <= 1e-4)
-        self.assertTrue(np.abs(diff).max() <= 5e-3)
+        # the heuristic value `7e-4` is obtained by running 50000 times (maximal value is around 3e-4).
+        assert np.abs(diff).mean() < 7e-4
+        # the heuristic value `8e-1` is obtained by running 50000 times (maximal value is around 5e-1).
+        assert np.abs(diff).max() < 8e-1
 
     @require_torch
     def test_double_precision_pad(self):