diff --git a/readthedocs/core/views/hooks.py b/readthedocs/core/views/hooks.py
index a99f66c1169..9140c45a59c 100644
--- a/readthedocs/core/views/hooks.py
+++ b/readthedocs/core/views/hooks.py
@@ -74,10 +74,10 @@ def build_branches(project, branch_list):
         to_build - a list of branches that were built
         not_building - a list of branches that we won't build
     """
+    to_build = set()
+    not_building = set()
     for branch in branch_list:
         versions = project.versions_from_branch_name(branch)
-        to_build = set()
-        not_building = set()
         for version in versions:
             log.info("(Branch Build) Processing %s:%s",
                      project.slug, version.slug)
diff --git a/readthedocs/restapi/views/integrations.py b/readthedocs/restapi/views/integrations.py
index 80699a1c196..ddc226cf472 100644
--- a/readthedocs/restapi/views/integrations.py
+++ b/readthedocs/restapi/views/integrations.py
@@ -233,7 +233,8 @@ def handle_webhook(self):
             try:
                 changes = self.request.data['push']['changes']
                 branches = [change['new']['name']
-                            for change in changes]
+                            for change in changes
+                            if change.get('new')]
                 return self.get_response_push(self.project, branches)
             except KeyError:
                 raise ParseError('Invalid request')
diff --git a/readthedocs/rtd_tests/tests/test_api.py b/readthedocs/rtd_tests/tests/test_api.py
index 75e2a7e1f34..219417c9a20 100644
--- a/readthedocs/rtd_tests/tests/test_api.py
+++ b/readthedocs/rtd_tests/tests/test_api.py
@@ -429,6 +429,22 @@ def test_bitbucket_webhook(self, trigger_build):
         trigger_build.assert_has_calls(
             [mock.call(force=True, version=mock.ANY, project=self.project)])
 
+        client.post(
+            '/api/v2/webhook/bitbucket/{0}/'.format(self.project.slug),
+            {
+                'push': {
+                    'changes': [
+                        {
+                            'new': None,
+                        },
+                    ],
+                },
+            },
+            format='json',
+        )
+        trigger_build.assert_not_called(
+            [mock.call(force=True, version=mock.ANY, project=self.project)])
+
     def test_bitbucket_invalid_webhook(self, trigger_build):
         """Bitbucket webhook unhandled event."""
         client = APIClient()