diff --git a/readthedocs/projects/models.py b/readthedocs/projects/models.py
index dada277f9ed..17e26731ca6 100644
--- a/readthedocs/projects/models.py
+++ b/readthedocs/projects/models.py
@@ -1068,15 +1068,21 @@ def update_stable_version(self):
         Return ``None`` if no update was made or if there is no version on the
         project that can be considered stable.
         """
+
+        # return immediately if the current stable is managed by the user and
+        # not automatically by Read the Docs (``machine=False``)
+        current_stable = self.get_stable_version()
+        if current_stable and not current_stable.machine:
+            return None
+
         versions = self.versions(manager=INTERNAL).all()
         new_stable = determine_stable_version(versions)
         if new_stable:
-            current_stable = self.get_stable_version()
             if current_stable:
                 identifier_updated = (
                     new_stable.identifier != current_stable.identifier
                 )
-                if identifier_updated and current_stable.machine:
+                if identifier_updated:
                     log.info(
                         'Update stable version: %(project)s:%(version)s',
                         {
diff --git a/readthedocs/rtd_tests/tests/test_project.py b/readthedocs/rtd_tests/tests/test_project.py
index 98fe04c0702..31294b99e7b 100644
--- a/readthedocs/rtd_tests/tests/test_project.py
+++ b/readthedocs/rtd_tests/tests/test_project.py
@@ -17,6 +17,7 @@
     LATEST,
     EXTERNAL,
 )
+from readthedocs.builds.constants import TAG
 from readthedocs.builds.models import Build, Version
 from readthedocs.oauth.services import GitHubService, GitLabService
 from readthedocs.projects.constants import GITHUB_BRAND, GITLAB_BRAND
@@ -184,6 +185,45 @@ def test_update_stable_version_excludes_external_versions(self):
         # Test that External Version is not considered for stable.
         self.assertEqual(self.pip.update_stable_version(), None)
 
+    def test_update_stable_version_machine_false(self):
+        # Initial stable version from fixture
+        self.assertEqual(self.pip.update_stable_version().slug, '0.8.1')
+
+        # None, when there is no stable to promote
+        self.assertEqual(self.pip.update_stable_version(), None)
+
+        get(
+            Version,
+            identifier='9.0',
+            verbose_name='9.0',
+            slug='9.0',
+            type=TAG,
+            project=self.pip,
+            active=True,
+        )
+        # New stable now is the newly created version
+        self.assertEqual(self.pip.update_stable_version().slug, '9.0')
+
+        # Make stable version machine=False
+        stable = self.pip.get_stable_version()
+        stable.machine = False
+        stable.save()
+
+        get(
+            Version,
+            identifier='10.0',
+            verbose_name='10.0',
+            slug='10.0',
+            type=TAG,
+            project=self.pip,
+            active=True,
+        )
+        # None, since the stable version is marked as machine=False and Read
+        # the Docs does not have control over it
+        with patch('readthedocs.projects.models.determine_stable_version') as m:
+            self.assertEqual(self.pip.update_stable_version(), None)
+            m.assert_not_called()
+
     def test_has_good_build_excludes_external_versions(self):
         # Delete all versions excluding External Versions.
         self.pip.versions.exclude(type=EXTERNAL).delete()