diff --git a/tests/test_items.py b/tests/test_items.py
index edf77a1..7f875ce 100644
--- a/tests/test_items.py
+++ b/tests/test_items.py
@@ -1,5 +1,6 @@
 import math
 import pickle
+import copy
 
 from datetime import date
 from datetime import datetime
@@ -860,3 +861,17 @@ def test_table_copy():
     table["foo"] = "baz"
     assert table_copy["foo"] == "bar"
     assert table_copy.as_string() == 'foo = "bar"\n'
+
+
+def test_copy_copy():
+    result = parse("""
+    [tool.poetry]
+    classifiers = [
+    # comment
+        "a",
+        "b",
+    ]
+    """)
+    classifiers = result["tool"]["poetry"]["classifiers"]
+    new = copy.copy(classifiers)
+    assert new == classifiers
diff --git a/tomlkit/items.py b/tomlkit/items.py
index 5128807..f4ca6d9 100644
--- a/tomlkit/items.py
+++ b/tomlkit/items.py
@@ -656,7 +656,6 @@ def as_string(self) -> str:
         return self._raw
 
     def __add__(self, other):
-
         return self._new(int(self._raw) + other)
 
     def __radd__(self, other):
@@ -1139,7 +1138,8 @@ def __init__(
     ) -> None:
         super().__init__(trivia)
         list.__init__(
-            self, [v.value for v in value if not isinstance(v, (Whitespace, Comment))]
+            self,
+            [v.value for v in value if not isinstance(v, (Whitespace, Comment, Null))],
         )
         self._index_map: Dict[int, int] = {}
         self._value = self._group_values(value)