diff --git a/ospd_openvas/lock.py b/ospd_openvas/lock.py
index 9aa23547..a11a5fdb 100644
--- a/ospd_openvas/lock.py
+++ b/ospd_openvas/lock.py
@@ -46,7 +46,7 @@ def acquire_lock(self) -> "LockFile":
             parent_dir = self._lock_file_path.parent
             parent_dir.mkdir(parents=True, exist_ok=True)
 
-            self._fd = open(self._lock_file_path, 'w')
+            self._fd = self._lock_file_path.open('w')
         except PermissionError as e:
             logger.error(
                 "Failed to create lock file %s. %s",
diff --git a/tests/test_lock.py b/tests/test_lock.py
index aef9da37..3a4d101f 100644
--- a/tests/test_lock.py
+++ b/tests/test_lock.py
@@ -25,6 +25,7 @@
 
 from unittest.mock import patch, MagicMock
 from ospd_openvas.lock import LockFile
+from .helper import assert_called_once
 
 
 class LockFileTestCase(unittest.TestCase):
@@ -55,7 +56,7 @@ def test_already_locked(self, mock_logger):
         lock_file = LockFile(lock_file_path)
         lock_file.acquire_lock()
         self.assertFalse(lock_file.has_lock())
-        mock_logger.error.assert_called_once()
+        assert_called_once(mock_logger.error)
 
         lock_file_aux.release_lock()
 
@@ -81,7 +82,7 @@ def test_create_paren_dirs_fail(self, mock_logger):
         lock_file.acquire_lock()
         self.assertFalse(lock_file.has_lock())
 
-        mock_logger.error.assert_called_once()
+        assert_called_once(mock_logger.error)
 
     def test_context_manager(self):
         lock_file_path = self.temp_dir / 'test.lock'