diff --git a/hooks.yaml b/hooks.yaml
index d501d50..eea7bed 100644
--- a/hooks.yaml
+++ b/hooks.yaml
@@ -110,7 +110,7 @@
     description: Sort the lines in specified files (defaults to alphabetical). You must provide list of target files as input in your .pre-commit-config.yaml file.
     entry: file-contents-sorter
     language: python
-    files: ''
+    files: '^$'
 -   id: fix-encoding-pragma
     name: Fix python encoding pragma
     language: python
diff --git a/tests/file_contents_sorter_test.py b/tests/file_contents_sorter_test.py
index e8f1ea8..7b3d098 100644
--- a/tests/file_contents_sorter_test.py
+++ b/tests/file_contents_sorter_test.py
@@ -2,7 +2,6 @@ import pytest
 
 from pre_commit_hooks.file_contents_sorter import FAIL
 from pre_commit_hooks.file_contents_sorter import main
-from pre_commit_hooks.file_contents_sorter import parse_commandline_input
 from pre_commit_hooks.file_contents_sorter import PASS
 
 
@@ -29,20 +28,3 @@ def test_integration(input_s, expected_retval, output, tmpdir):
 
     assert path.read_binary() == output
     assert output_retval == expected_retval
-
-
-def test_parse_commandline_input_errors_without_args():
-    with pytest.raises(SystemExit):
-        parse_commandline_input([])
-
-
-@pytest.mark.parametrize(
-    ('filename_list'),
-    (
-        ['filename1'],
-        ['filename1', 'filename2'],
-    )
-)
-def test_parse_commandline_input_success(filename_list):
-    args = parse_commandline_input(filename_list)
-    assert args.filenames == filename_list