diff --git a/bob/learn/tensorflow/tests/data/db_to_tfrecords_config.py b/bob/learn/tensorflow/tests/data/db_to_tfrecords_config.py
index 52799ddd8bf9cd2c1cbf2f52bab0419c90678d62..637d8c551b37859242b3148918e478ee4eb7e87d 100644
--- a/bob/learn/tensorflow/tests/data/db_to_tfrecords_config.py
+++ b/bob/learn/tensorflow/tests/data/db_to_tfrecords_config.py
@@ -4,7 +4,10 @@ from bob.learn.tensorflow.data import dataset_using_generator
 mnist = tf.keras.datasets.mnist
 
 (x_train, y_train), (_, _) = mnist.load_data()
-samples = (tf.keras.backend.arange(len(x_train)), x_train, y_train)
+samples = [
+    [a, b, c]
+    for a, b, c in zip(tf.keras.backend.arange(len(x_train)), x_train, y_train)
+]
 
 
 def reader(sample):