diff --git a/tests/test_items.py b/tests/test_items.py
index 94418bf..cefb29e 100644
--- a/tests/test_items.py
+++ b/tests/test_items.py
@@ -129,6 +129,19 @@ def test_aot_unwrap():
             assert_is_ppo(vu, str)
 
 
+def test_aot_set_item():
+    d = item(["A", {"b": "B"}, ["c", "D"]])
+    d[0] = "C"
+    assert isinstance(d[0], String)
+    assert d[0] == "C"
+    d[1]["b"] = "D"
+    assert isinstance(d[1], InlineTable)
+    assert d[1]["b"] == "D"
+    d[0] = ["c", "C"]
+    assert isinstance(d[0], Array)
+    assert d[0][1] == "C"
+
+
 def test_time_unwrap():
     t = time(3, 8, 14)
     elementary_test(item(t), time)
diff --git a/tomlkit/items.py b/tomlkit/items.py
index b80e9f1..dcb0463 100644
--- a/tomlkit/items.py
+++ b/tomlkit/items.py
@@ -1885,7 +1885,7 @@ def __getitem__(self, key):
         return self._body[key]
 
     def __setitem__(self, key: slice | int, value: Any) -> None:
-        raise NotImplementedError
+        self._body[key] = item(value, _parent=self)
 
     def __delitem__(self, key: slice | int) -> None:
         del self._body[key]