diff --git a/python/dp_auditorium/dp_auditorium/testers/hockey_stick_tester.py b/python/dp_auditorium/dp_auditorium/testers/hockey_stick_tester.py
index a8b6bbc7..1b61eaea 100644
--- a/python/dp_auditorium/dp_auditorium/testers/hockey_stick_tester.py
+++ b/python/dp_auditorium/dp_auditorium/testers/hockey_stick_tester.py
@@ -193,7 +193,7 @@ def _get_optimized_divergence_estimation_model(
             self._training_options.optimizer_learning_rate
         ),
         loss=tf.keras.losses.BinaryCrossentropy(from_logits=True),
-        metrics=tf.keras.metrics.BinaryAccuracy(threshold=0.0),
+        metrics=[tf.keras.metrics.BinaryAccuracy(threshold=0.0)],
     )
     features, labels = self._generate_inputs_to_model(
         samples_first_distribution,