diff --git a/rag/app/qa.py b/rag/app/qa.py
index 8843c0a6e0..7a55f32d3d 100644
--- a/rag/app/qa.py
+++ b/rag/app/qa.py
@@ -395,7 +395,7 @@ def chunk(filename, binary=None, from_page=0, to_page=MAXIMUM_PAGE_NUMBER, lang=
                     f"{len(fails)} failure, line: %s..." % (",".join(fails[:3])) if fails else "")))
 
         if question:
-            res.append(beAdoc(deepcopy(doc), question, answer, eng, len(list(reader))))
+            res.append(beAdoc(deepcopy(doc), question, answer, eng, len(lines)))
 
         callback(0.6, ("Extract Q&A: {}".format(len(res)) + (
             f"{len(fails)} failure, line: %s..." % (",".join(fails[:3])) if fails else "")))
diff --git a/test/unit_test/rag/app/test_qa_csv.py b/test/unit_test/rag/app/test_qa_csv.py
new file mode 100644
index 0000000000..04897fe65b
--- /dev/null
+++ b/test/unit_test/rag/app/test_qa_csv.py
@@ -0,0 +1,54 @@
+#
+#  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+from __future__ import annotations
+
+import warnings
+
+with warnings.catch_warnings():
+    warnings.filterwarnings("ignore", message=".*pkg_resources is deprecated.*", category=UserWarning)
+    import pkg_resources  # noqa: F401 - stabilize xgboost import during collection
+
+import pytest
+
+from rag.app import qa
+
+
+def _noop_callback(*_args, **_kwargs):
+    pass
+
+
+@pytest.fixture(autouse=True)
+def _stub_rag_tokenizer(monkeypatch):
+    def fake_tokenize(text):
+        return str(text)
+
+    monkeypatch.setattr("rag.nlp.rag_tokenizer.tokenize", fake_tokenize)
+    monkeypatch.setattr("rag.nlp.rag_tokenizer.fine_grained_tokenize", fake_tokenize)
+
+
+@pytest.mark.p2
+def test_csv_final_pair_uses_last_line_number():
+    chunks = qa.chunk(
+        "qa.csv",
+        binary=b"Question 1,Answer 1\nQuestion 2,Answer 2",
+        lang="English",
+        callback=_noop_callback,
+    )
+
+    assert len(chunks) == 2
+    assert chunks[0]["top_int"] == [1]
+    assert chunks[1]["top_int"] == [2]