diff --git a/docs/changelog.rst b/docs/changelog.rst
index a0d27c1c..1824f6f9 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -29,6 +29,8 @@ In progress (unreleased)
 * :gh:issue:`1118` CI: Add OS release coverage: Ubuntu 22.04, Ubuntu 24.04
 * :gh:issue:`1124` :mod:`mitogen`: Log why a module is sent or not sent by
   :class:`mitogen.master.ModuleResponder`
+* :gh:issue:`1124` :mod:`ansible_mitogen`: Speedup startup by not sending
+  ``__main__`` as a related module
 
 
 v0.3.33 (2025-11-22)
diff --git a/mitogen/master.py b/mitogen/master.py
index 4de32586..e495197d 100644
--- a/mitogen/master.py
+++ b/mitogen/master.py
@@ -843,6 +843,12 @@ class ModuleFinder(object):
     related modules likely needed by a child context requesting the original
     module.
     """
+
+    # Fullnames of modules that should not be sent as a related module
+    _related_modules_denylist = frozenset({
+        '__main__',
+    })
+
     def __init__(self):
         #: Import machinery is expensive, keep :py:meth`:get_module_source`
         #: results around.
@@ -954,6 +960,9 @@ class ModuleFinder(object):
         if 'six.moves' in related_fullname:
             return _log_reject('six.moves avoidence')
 
+        if related_fullname in self._related_modules_denylist:
+            return _log_reject('on denylist')
+
         return False
 
     def find_related_imports(self, fullname):