diff --git a/src/flake8/options/manager.py b/src/flake8/options/manager.py
index a5e5906..2594865 100644
--- a/src/flake8/options/manager.py
+++ b/src/flake8/options/manager.py
@@ -426,12 +426,16 @@ class OptionManager(object):
         )
 
     def parse_args(self, args=None, values=None):
+        # type: (Optional[List[str]], Optional[argparse.Namespace]) -> Tuple[argparse.Namespace, List[str]]  # noqa: E501
         """Proxy to calling the OptionParser's parse_args method."""
         self.generate_epilog()
         self.update_version_string()
-        args = self.parser.parse_args(args, values)
+        assert isinstance(  # nosec (for bandit)
+            self.parser, argparse.ArgumentParser
+        ), self.parser
+        parsed_args = self.parser.parse_args(args, values)
         # TODO: refactor callers to not need this
-        return args, args.filenames
+        return parsed_args, parsed_args.filenames
 
     def parse_known_args(self, args=None):
         # type: (Optional[List[str]]) -> Tuple[argparse.Namespace, List[str]]