diff --git a/lib/cli/src/crewai_cli/update_crew.py b/lib/cli/src/crewai_cli/update_crew.py
index 3935e2f5f..db250fda7 100644
--- a/lib/cli/src/crewai_cli/update_crew.py
+++ b/lib/cli/src/crewai_cli/update_crew.py
@@ -89,7 +89,7 @@ def migrate_pyproject(input_file: str, output_file: str) -> None:
     lock_file = "poetry.lock"
     lock_backup = "poetry-old.lock"
     if os.path.exists(lock_file):
-        os.rename(lock_file, lock_backup)
+        os.replace(lock_file, lock_backup)
     else:
         pass
 
diff --git a/lib/cli/tests/test_update_crew.py b/lib/cli/tests/test_update_crew.py
new file mode 100644
index 000000000..751074df2
--- /dev/null
+++ b/lib/cli/tests/test_update_crew.py
@@ -0,0 +1,63 @@
+"""Tests for the ``crewai update`` pyproject migration."""
+
+from pathlib import Path
+
+import pytest
+
+from crewai_cli.update_crew import migrate_pyproject
+
+
+_POETRY_PYPROJECT = """\
+[tool.poetry]
+name = "demo"
+version = "0.1.0"
+description = "demo crew"
+authors = ["Demo Author <demo@example.com>"]
+
+[tool.poetry.dependencies]
+python = ">=3.10,<3.14"
+crewai = "^1.0.0"
+"""
+
+
+def _write_project(tmp_path: Path) -> None:
+    """Create a minimal Poetry-style project with a lock file in ``tmp_path``."""
+    (tmp_path / "pyproject.toml").write_text(_POETRY_PYPROJECT, encoding="utf-8")
+    (tmp_path / "poetry.lock").write_text("current lock\n", encoding="utf-8")
+
+
+def test_migrate_pyproject_backs_up_lock_file(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """The migration renames ``poetry.lock`` to ``poetry-old.lock`` and backs up pyproject."""
+    monkeypatch.chdir(tmp_path)
+    _write_project(tmp_path)
+
+    migrate_pyproject("pyproject.toml", "pyproject.toml")
+
+    assert not (tmp_path / "poetry.lock").exists()
+    assert (tmp_path / "poetry-old.lock").read_text(encoding="utf-8") == (
+        "current lock\n"
+    )
+    assert (tmp_path / "pyproject-old.toml").exists()
+
+
+def test_migrate_pyproject_overwrites_existing_lock_backup(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """A second ``crewai update`` must replace a stale ``poetry-old.lock``.
+
+    ``os.rename`` refuses to overwrite an existing destination on Windows
+    (``FileExistsError``) while POSIX replaces it silently, so re-running the
+    migration used to fail only on Windows.
+    """
+    monkeypatch.chdir(tmp_path)
+    _write_project(tmp_path)
+    (tmp_path / "poetry-old.lock").write_text("stale backup\n", encoding="utf-8")
+
+    migrate_pyproject("pyproject.toml", "pyproject.toml")
+
+    assert not (tmp_path / "poetry.lock").exists()
+    assert (tmp_path / "poetry-old.lock").read_text(encoding="utf-8") == (
+        "current lock\n"
+    )