diff --git a/src/mdformat/_cli.py b/src/mdformat/_cli.py
index 5d049c6..11899b7 100644
--- a/src/mdformat/_cli.py
+++ b/src/mdformat/_cli.py
@@ -3,7 +3,6 @@
 import argparse
 from collections.abc import Generator, Iterable, Mapping, Sequence
 import contextlib
-import inspect
 import logging
 import os.path
 from pathlib import Path
@@ -426,12 +425,6 @@ def log_handler_applied(
         logger.removeHandler(handler)
 
 
-def get_package_name(obj: object) -> str | None:
-    """Return top level module name, or None if not found."""
-    module = inspect.getmodule(obj)
-    return module.__name__.split(".", maxsplit=1)[0] if module else None
-
-
 def get_plugin_info_str(
     parser_extension_dists: Mapping[str, tuple[str, list[str]]],
     codeformatter_dists: Mapping[str, tuple[str, list[str]]],
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 97461c4..22f488e 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -6,7 +6,7 @@
 import pytest
 
 import mdformat
-from mdformat._cli import get_package_name, get_plugin_info_str, run, wrap_paragraphs
+from mdformat._cli import get_plugin_info_str, run, wrap_paragraphs
 from mdformat.plugins import CODEFORMATTERS, PARSER_EXTENSIONS
 from tests.utils import (
     FORMATTED_MARKDOWN,
@@ -345,13 +345,6 @@ def test_eol__check_keep_crlf(tmp_path):
     assert run((str(file_path), "--check", "--end-of-line=keep")) == 1
 
 
-def test_get_package_name():
-    # Test a function/class
-    assert get_package_name(patch) == "unittest"
-    # Test a package/module
-    assert get_package_name(mdformat) == "mdformat"
-
-
 def test_get_plugin_info_str():
     info = get_plugin_info_str(
         {"mdformat-tables": ("0.1.0", ["tables"])},