diff --git a/Lib/test/test_ttk/test_style.py b/Lib/test/test_ttk/test_style.py
index 56d8a5931fdfa5..d2506db9fb75ba 100644
--- a/Lib/test/test_ttk/test_style.py
+++ b/Lib/test/test_ttk/test_style.py
@@ -161,9 +161,18 @@ def test_configure_custom_copy(self):
                     newname = f'C.{name}'
                     self.assertEqual(style.configure(newname), None)
                     style.configure(newname, **default)
-                    self.assertEqual(style.configure(newname), default)
+                    # gh-128846: on 3.13 the aqua theme with Tk 9 reports an
+                    # unset option as an empty tuple in the original style but
+                    # as an empty string in the copy.  Normalize the copy back
+                    # to the empty tuple before comparing.
+                    def norm(value):
+                        return () if value == '' else value
+                    copy = style.configure(newname)
+                    self.assertEqual({k: norm(v) for k, v in copy.items()},
+                                     default)
                     for key, value in default.items():
-                        self.assertEqual(style.configure(newname, key), value)
+                        self.assertEqual(norm(style.configure(newname, key)),
+                                         value)
 
 
     def test_map_custom_copy(self):