diff --git a/datar/all.py b/datar/all.py
index 299b4772..9ea43448 100644
--- a/datar/all.py
+++ b/datar/all.py
@@ -15,7 +15,23 @@
 
 __all__ = [key for key in locals() if not key.startswith("_")]
 
-if get_option("allow_conflict_names"):  # noqa: F405 pragma: no cover
+if get_option("allow_conflict_names"):  # noqa: F405
     __all__.extend(_base_conflict_names | _dplyr_conflict_names)
     for name in _base_conflict_names | _dplyr_conflict_names:
         locals()[name] = locals()[name + "_"]
+
+
+def __getattr__(name):
+    """Even when allow_conflict_names is False, datar.base.sum should be fine
+    """
+    if name in _base_conflict_names | _dplyr_conflict_names:
+        import sys
+        import ast
+        from executing import Source
+        node = Source.executing(sys._getframe(1)).node
+        if isinstance(node, (ast.Call, ast.Attribute)):
+            # import datar.all as d
+            # d.sum(...) or getattr(d, "sum")(...)
+            return globals()[name + "_"]
+
+    raise AttributeError
diff --git a/datar/base.py b/datar/base.py
index c36a2f29..6c156291 100644
--- a/datar/base.py
+++ b/datar/base.py
@@ -6,7 +6,23 @@
 __all__ = [key for key in locals() if not key.startswith("_")]
 _conflict_names = {"min", "max", "sum", "abs", "round", "all", "any", "re"}
 
-if get_option("allow_conflict_names"):  # noqa: F405 pragma: no cover
+if get_option("allow_conflict_names"):  # noqa: F405
     __all__.extend(_conflict_names)
     for name in _conflict_names:
         locals()[name] = locals()[name + "_"]
+
+
+def __getattr__(name):
+    """Even when allow_conflict_names is False, datar.base.sum should be fine
+    """
+    if name in _conflict_names:
+        import sys
+        import ast
+        from executing import Source
+        node = Source.executing(sys._getframe(1)).node
+        if isinstance(node, (ast.Call, ast.Attribute)):
+            # import datar.base as d
+            # d.sum(...)
+            return globals()[name + "_"]
+
+    raise AttributeError
diff --git a/datar/dplyr.py b/datar/dplyr.py
index 3c609e51..6f71cb61 100644
--- a/datar/dplyr.py
+++ b/datar/dplyr.py
@@ -7,7 +7,23 @@
 __all__ = [key for key in locals() if not key.startswith("_")]
 _conflict_names = {"filter", "slice"}
 
-if _get_option("allow_conflict_names"):  # pragma: no cover
+if _get_option("allow_conflict_names"):
     __all__.extend(_conflict_names)
     for name in _conflict_names:
         locals()[name] = locals()[name + "_"]
+
+
+def __getattr__(name):
+    """Even when allow_conflict_names is False, datar.base.sum should be fine
+    """
+    if name in _conflict_names:
+        import sys
+        import ast
+        from executing import Source
+        node = Source.executing(sys._getframe(1)).node
+        if isinstance(node, (ast.Call, ast.Attribute)):
+            # import datar.dplyr as d
+            # d.sum(...)
+            return globals()[name + "_"]
+
+    raise AttributeError
diff --git a/poetry.lock b/poetry.lock
index 9eb869db..6e17e83a 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -88,47 +88,47 @@ toml = ["tomli"]
 
 [[package]]
 name = "datar-arrow"
-version = "0.0.0"
+version = "0.0.1"
 description = "The pyarrow backend for datar"
 optional = true
 python-versions = ">=3.8,<4.0"
 files = [
-    {file = "datar_arrow-0.0.0-py3-none-any.whl", hash = "sha256:41ddc5d3171ac76433c20380178a12e9f08a6761ea930c5626a843a2e5dba21b"},
-    {file = "datar_arrow-0.0.0.tar.gz", hash = "sha256:1c713201830ed9232a4892ce73aa6a834d5cbe3c885ae5629b666749b1be4a86"},
+    {file = "datar_arrow-0.0.1-py3-none-any.whl", hash = "sha256:20a0ead1d3bf74b800d1e0255647ed7bc287f546aca0d88b9f8489286ea5d553"},
+    {file = "datar_arrow-0.0.1.tar.gz", hash = "sha256:0b4f8f4eb5446e0b64306def93ae63741f7c6099a24a59b13763b2037202842f"},
 ]
 
 [package.dependencies]
-datar = ">=0.12,<0.13"
+datar = ">=0.13,<0.14"
 pyarrow = ">=11,<12"
 
 [[package]]
 name = "datar-numpy"
-version = "0.2.0"
+version = "0.2.1"
 description = "The numpy backend for datar"
 optional = true
 python-versions = ">=3.8,<4.0"
 files = [
-    {file = "datar_numpy-0.2.0-py3-none-any.whl", hash = "sha256:2369f3d8419e7ffbbe950ad6b459a3f75ae6571155fab09f63874d49e96bab6b"},
-    {file = "datar_numpy-0.2.0.tar.gz", hash = "sha256:a0e119f3ec208ba45100e31b22a8dc1d0a926a42f144bb5b2b859e2897d2e320"},
+    {file = "datar_numpy-0.2.1-py3-none-any.whl", hash = "sha256:f9a85e514c612d6c400514f75242648d17c340aff188d8b8cf94d0a0de157bab"},
+    {file = "datar_numpy-0.2.1.tar.gz", hash = "sha256:49d835f6fdbd856cd7ea00d2829da664b2138be40892d72be464d0df79b5252a"},
 ]
 
 [package.dependencies]
-datar = ">=0.12,<0.13"
+datar = ">=0.13,<0.14"
 numpy = ">=1.20,<2.0"
 
 [[package]]
 name = "datar-pandas"
-version = "0.3.0"
+version = "0.3.1"
 description = "The pandas backend for datar"
 optional = true
 python-versions = ">=3.8,<4.0"
 files = [
-    {file = "datar_pandas-0.3.0-py3-none-any.whl", hash = "sha256:738190a54c816dd3fa1529d0f48a601b134edc52a3e1d11ce6d3d0bcec91c2a7"},
-    {file = "datar_pandas-0.3.0.tar.gz", hash = "sha256:97803e124f0e3ac2f6b65ddd087859fabb47e5d510fc1f4d3772a882853dbea9"},
+    {file = "datar_pandas-0.3.1-py3-none-any.whl", hash = "sha256:ccd5db148b2d5a5d76aa408ea8b2b33b6bb4b4cc0a47d84062de980ef42a91f2"},
+    {file = "datar_pandas-0.3.1.tar.gz", hash = "sha256:2d683cca9eb1991fe19e0669b41242dfed66e0d65d183e3c76a0014376e1a051"},
 ]
 
 [package.dependencies]
-datar = ">=0.12,<0.13"
+datar = ">=0.13,<0.14"
 datar-numpy = ">=0.2,<0.3"
 pdtypes = ">=0.0.4,<0.0.5"
 
diff --git a/tests/conflict_names.py b/tests/conflict_names.py
new file mode 100644
index 00000000..f243e6ac
--- /dev/null
+++ b/tests/conflict_names.py
@@ -0,0 +1,112 @@
+import argparse
+
+
+def test_getattr(module, allow_conflict_names, fun, error):
+    from datar import options
+    options(allow_conflict_names=allow_conflict_names)
+
+    if module == "all":
+        import datar.all as d
+    elif module == "base":
+        import datar.base as d
+    elif module == "dplyr":
+        import datar.dplyr as d
+
+    if not error:
+        return getattr(d, fun)
+
+    try:
+        getattr(d, fun)
+    except Exception as e:
+        raised = type(e).__name__
+        assert raised == error, f"Raised {raised}, expected {error}"
+    else:
+        raise AssertionError(f"{error} should have raised")
+
+
+def _import(module, fun):
+    if module == "all" and fun == "sum":
+        from datar.all import sum  # noqa: F401
+    elif module == "all" and fun == "slice":
+        from datar.all import slice  # noqa: F401
+    elif module == "base" and fun == "sum":
+        from datar.base import sum  # noqa: F401
+    elif module == "dplyr" and fun == "slice":
+        from datar.dplyr import slice  # noqa: F401
+
+
+def test_import(module, allow_conflict_names, fun, error):
+    from datar import options
+    options(allow_conflict_names=allow_conflict_names)
+
+    if not error:
+        return _import(module, fun)
+
+    try:
+        _import(module, fun)
+    except Exception as e:
+        raised = type(e).__name__
+        assert raised == error, f"Raised {raised}, expected {error}"
+    else:
+        raise AssertionError(f"{error} should have raised")
+
+
+def make_test(module, allow_conflict_names, getattr, fun, error):
+    if fun == "_":
+        fun = "sum" if module in ["all", "base"] else "slice"
+
+    if getattr:
+        return test_getattr(module, allow_conflict_names, fun, error)
+
+    return test_import(module, allow_conflict_names, fun, error)
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "--module",
+        choices=["all", "base", "dplyr"],
+        required=True,
+        help="The module to test"
+    )
+    parser.add_argument(
+        "--allow-conflict-names",
+        action="store_true",
+        help="Whether to allow conflict names",
+        default=False,
+    )
+    parser.add_argument(
+        "--getattr",
+        action="store_true",
+        help=(
+            "Whether to test datar.all.sum, "
+            "otherwise test from datar.all import sum."
+        ),
+        default=False,
+    )
+    parser.add_argument(
+        "--fun",
+        help=(
+            "The function to test. "
+            "If _ then sum for all/base, slice for dplyr"
+        ),
+        choices=["sum", "filter", "_"],
+        default="_",
+    )
+    parser.add_argument(
+        "--error",
+        help="The error to expect",
+    )
+    args = parser.parse_args()
+
+    make_test(
+        args.module,
+        args.allow_conflict_names,
+        args.getattr,
+        args.fun,
+        args.error,
+    )
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tests/test_conflict_names.py b/tests/test_conflict_names.py
new file mode 100644
index 00000000..46ac9109
--- /dev/null
+++ b/tests/test_conflict_names.py
@@ -0,0 +1,85 @@
+import sys
+import subprocess
+from pathlib import Path
+
+import pytest
+
+
+def _run_conflict_names(module, allow_conflict_names, getat, error):
+    here = Path(__file__).parent
+    conflict_names = here / "conflict_names.py"
+    cmd = [
+        sys.executable,
+        str(conflict_names),
+        "--module",
+        module,
+    ]
+    if error:
+        cmd += ["--error", error]
+    if allow_conflict_names:
+        cmd.append("--allow-conflict-names")
+    if getat:
+        cmd.append("--getattr")
+
+    p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    return p.wait(), " ".join(cmd)
+
+
+def test_from_all_import_allow_conflict_names_true():
+    r, cmd = _run_conflict_names("all", True, False, None)
+    assert r == 0, cmd
+
+
+def test_from_all_import_allow_conflict_names_false():
+    r, cmd = _run_conflict_names("all", False, False, "ImportError")
+    assert r == 0, cmd
+
+
+def test_all_getattr_allow_conflict_names_true():
+    r, cmd = _run_conflict_names("all", True, True, None)
+    assert r == 0, cmd
+
+
+def test_all_getattr_allow_conflict_names_false():
+    r, cmd = _run_conflict_names("all", False, True, None)
+    assert r == 0, cmd
+
+
+def test_from_base_import_allow_conflict_names_true():
+    r, cmd = _run_conflict_names("base", True, False, None)
+    assert r == 0, cmd
+
+
+def test_from_base_import_allow_conflict_names_false():
+    r, cmd = _run_conflict_names("base", False, False, "ImportError")
+    assert r == 0, cmd
+
+
+def test_base_getattr_allow_conflict_names_true():
+    r, cmd = _run_conflict_names("base", True, True, None)
+    assert r == 0, cmd
+
+
+def test_base_getattr_allow_conflict_names_false():
+    r, cmd = _run_conflict_names("base", False, True, None)
+    assert r == 0, cmd
+
+
+def test_from_dplyr_import_allow_conflict_names_true():
+    r, cmd = _run_conflict_names("dplyr", True, False, None)
+    assert r == 0, cmd
+
+
+def test_from_dplyr_import_allow_conflict_names_false():
+    r, cmd = _run_conflict_names("dplyr", False, False, "ImportError")
+    assert r == 0, cmd
+
+
+def test_dplyr_getattr_allow_conflict_names_true():
+    r, cmd = _run_conflict_names("dplyr", True, True, None)
+    assert r == 0, cmd
+
+
+def test_dplyr_getattr_allow_conflict_names_false():
+    r, cmd = _run_conflict_names("dplyr", False, True, None)
+    assert r == 0, cmd
diff --git a/tox.ini b/tox.ini
index 75b7e9b7..9974eb94 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,4 +14,5 @@ per-file-ignores =
     datar/base.py: F401, F402, F403, E402
     datar/dplyr.py: F401, F402, F403, E402
     datar/data/metadata.py: E501
+    tests/test_conflict_names.py: F401
 max-line-length = 81