diff --git a/readthedocs/rtd_tests/tests/test_config_integration.py b/readthedocs/rtd_tests/tests/test_config_integration.py
index 264965ac1dd..1db2f85688f 100644
--- a/readthedocs/rtd_tests/tests/test_config_integration.py
+++ b/readthedocs/rtd_tests/tests/test_config_integration.py
@@ -75,6 +75,7 @@ def setUp(self):
             Project,
             main_language_project=None,
             install_project=False,
+            container_image=None,
         )
         self.version = get(Version, project=self.project)
 
diff --git a/readthedocs/settings/base.py b/readthedocs/settings/base.py
index 91d84c8bd0d..e91fd8e6cf5 100644
--- a/readthedocs/settings/base.py
+++ b/readthedocs/settings/base.py
@@ -367,6 +367,9 @@ def USE_PROMOS(self):  # noqa
         'readthedocs/build:5.0': {
             'python': {'supported_versions': [2, 2.7, 3, 3.5, 3.6, 3.7, 'pypy3.5']},
         },
+        'readthedocs/build:6.0rc1': {
+            'python': {'supported_versions': [2, 2.7, 3, 3.5, 3.6, 3.7, 3.8, 'pypy3.5']},
+        },
     }
 
     # Alias tagged via ``docker tag`` on the build servers