diff --git a/services/ml_helpers.py b/services/ml_helpers.py
index c4650b4..d05a582 100644
--- a/services/ml_helpers.py
+++ b/services/ml_helpers.py
@@ -8,6 +8,7 @@
 feature extraction, so that the serving code and training code both use the same
 set of features.
 """
+# TODO(crbug.com/monorail/7515): DELETE THIS FILE and all references.
 
 from __future__ import division
 from __future__ import print_function