diff --git a/docarray/array/doc_list/doc_list.py b/docarray/array/doc_list/doc_list.py
index 07d3d37fedd..c88f68903b2 100644
--- a/docarray/array/doc_list/doc_list.py
+++ b/docarray/array/doc_list/doc_list.py
@@ -171,7 +171,7 @@ def append(self, doc: T_doc):
         as the `.doc_type` of this `DocList` otherwise it will fail.
         :param doc: A Document
         """
-        super().append(self._validate_one_doc(doc))
+        return super().append(self._validate_one_doc(doc))
 
     def extend(self, docs: Iterable[T_doc]):
         """
@@ -180,7 +180,14 @@ def extend(self, docs: Iterable[T_doc]):
         fail.
         :param docs: Iterable of Documents
         """
-        super().extend(self._validate_docs(docs))
+        it: Iterable[T_doc] = list()
+        if self is docs:
+            # see https://github.com/docarray/docarray/issues/1489
+            it = list(docs)
+        else:
+            it = self._validate_docs(docs)
+
+        return super().extend(it)
 
     def insert(self, i: SupportsIndex, doc: T_doc):
         """
diff --git a/tests/units/array/test_array.py b/tests/units/array/test_array.py
index 33344bd2aaa..b72a42292a4 100644
--- a/tests/units/array/test_array.py
+++ b/tests/units/array/test_array.py
@@ -53,6 +53,17 @@ class Text(BaseDoc):
         assert da.id == str(i)
 
 
+def test_extend_itself():
+    class Text(BaseDoc):
+        text: str
+
+    da = DocList[Text]([Text(text='hello', id=str(i)) for i in range(10)])
+
+    da.extend(da)
+
+    assert len(da) == 20
+
+
 def test_slice(da):
     da2 = da[0:5]
     assert type(da2) == da.__class__
@@ -331,7 +342,7 @@ class Doc(BaseDoc):
     texts = da_sliced.text
     assert len(texts) == 5
     for i, text in enumerate(texts):
-        assert text == f'hello{i*2}'
+        assert text == f'hello{i * 2}'
 
 
 def test_del_item(da):