diff --git a/Lib/test/test_selectors.py b/Lib/test/test_selectors.py
index 15f71c11831..9521481901b 100644
--- a/Lib/test/test_selectors.py
+++ b/Lib/test/test_selectors.py
@@ -323,6 +323,8 @@ class BaseSelectorTestCase(unittest.TestCase):
     @unittest.skipIf(sys.platform == 'win32',
                      'select.select() cannot be used with empty fd sets')
     def test_empty_select(self):
+        # Issue #23009: Make sure EpollSelector.select() works when no FD is
+        # registered.
         s = self.SELECTOR()
         self.addCleanup(s.close)
         self.assertEqual(s.select(timeout=0), [])