diff --git a/tests/no_commit_to_branch_test.py b/tests/no_commit_to_branch_test.py
index 1cb69e2..ccd83e4 100644
--- a/tests/no_commit_to_branch_test.py
+++ b/tests/no_commit_to_branch_test.py
@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from unittest.mock import patch
+
 import pytest
 
 from pre_commit_hooks.no_commit_to_branch import _default_branch
@@ -81,6 +83,14 @@ def test_default_branch_names(temp_git_dir, branch_name):
         assert main(()) == 1
 
 
+def test_default_branch_falls_back_when_empty_branch(tmpdir):
+    with patch(
+        'pre_commit_hooks.no_commit_to_branch.cmd_output',
+        return_value='origin/',
+    ):
+        assert _default_branch() == frozenset({'master', 'main'})
+
+
 def test_default_branch_detects_from_origin(tmpdir):
     remote = tmpdir.join('remote')
     cmd_output('git', 'init', '--', str(remote))