diff --git a/ddsp/training/data_preparation/prepare_tfrecord_lib.py b/ddsp/training/data_preparation/prepare_tfrecord_lib.py
index 7ca22f21..2f150be6 100644
--- a/ddsp/training/data_preparation/prepare_tfrecord_lib.py
+++ b/ddsp/training/data_preparation/prepare_tfrecord_lib.py
@@ -175,7 +175,7 @@ def prepare_tfrecord(input_audio_paths,
                      chunk_secs=20.0,
                      center=False,
                      viterbi=True,
-                     pipeline_options=''):
+                     pipeline_options=()):
   """Prepares a TFRecord for use in training, evaluation, and prediction.
 
   Args:
diff --git a/setup.py b/setup.py
index 2cc529f7..1c142e4d 100644
--- a/setup.py
+++ b/setup.py
@@ -38,6 +38,7 @@
     scripts=[],
     install_requires=[
         'absl-py',
+        'apache-beam',
         'cloudml-hypertune<=0.1.0.dev6',
         'crepe<=0.0.12',
         'dill<=0.3.4',