diff --git a/tensorflow/tools/docs/generate2.py b/tensorflow/tools/docs/generate2.py
index 8a63b831224..039654323bd 100644
--- a/tensorflow/tools/docs/generate2.py
+++ b/tensorflow/tools/docs/generate2.py
@@ -112,9 +112,9 @@ def build_docs(output_dir, code_url_prefix, search_hints=True):
 
   code_url_prefixes = (
       code_url_prefix,
-      # External packages source repositories
-      "https://github.com/tensorflow/tensorboard/tree/master/tensorboard"
-      "https://github.com/tensorflow/estimator/tree/master/tensorflow_estimator"
+      # External packages source repositories,
+      "https://github.com/tensorflow/tensorboard/tree/master/tensorboard",
+      "https://github.com/tensorflow/estimator/tree/master/tensorflow_estimator",
   )
 
   doc_generator = generate_lib.DocGenerator(