diff --git a/git_cl.py b/git_cl.py
index 8ba9e31527..1ae46c6862 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -1919,6 +1919,10 @@ class Changelist(object):
 
   @staticmethod
   def _BuildCommentSummary(msg, comments, readable):
+    if 'email' not in msg['author']:
+      # Some bot accounts may not have an email associated.
+      return None
+
     key = (msg['author']['email'], msg['date'])
     # Don't bother showing autogenerated messages that don't have associated
     # file or line comments. this will filter out most autogenerated
diff --git a/tests/git_cl_test.py b/tests/git_cl_test.py
index 653b940c46..a88c5e3a2a 100755
--- a/tests/git_cl_test.py
+++ b/tests/git_cl_test.py
@@ -2663,6 +2663,16 @@ class TestGitCl(unittest.TestCase):
              u'id': u'f5a6c25ecbd3b3b54a43ae418ed97eff046d4568',
              u'message': u'Patch Set 2: Code-Review+1',
           },
+          {
+             u'_revision_number': 2,
+             u'author': {
+               u'_account_id': 42,
+               u'name': u'reviewer'
+             },
+             u'date': u'2017-03-17 05:19:37.900000000',
+             u'id': u'f5a6c25ecbd3b3b54a43ae418ed97eff046d0000',
+             u'message': u'A bot with no email set',
+          },
         ]
       }
     self.calls = [