diff --git a/qutebrowser/utils/jinja.py b/qutebrowser/utils/jinja.py
index 7dee80249..e6ccd9c6c 100644
--- a/qutebrowser/utils/jinja.py
+++ b/qutebrowser/utils/jinja.py
@@ -80,7 +80,8 @@ def render(template, **kwargs):
         return _env.get_template(template).render(**kwargs)
     except jinja2.exceptions.UndefinedError:
         log.misc.exception("UndefinedError while rendering " + template)
-        err_template = utils.read_file(os.path.join('html', 'undef_error.html'))
+        err_path = os.path.join('html', 'undef_error.html')
+        err_template = utils.read_file(err_path)
         tb = traceback.format_exc()
         return err_template.format(pagename=template, traceback=tb)
 
diff --git a/tests/unit/utils/test_jinja.py b/tests/unit/utils/test_jinja.py
index 6852e4051..cea237d22 100644
--- a/tests/unit/utils/test_jinja.py
+++ b/tests/unit/utils/test_jinja.py
@@ -34,6 +34,7 @@ from qutebrowser.utils import utils, jinja
 def patch_read_file(monkeypatch):
     """pytest fixture to patch utils.read_file."""
     real_read_file = utils.read_file
+
     def _read_file(path):
         """A read_file which returns a simple template if the path is right."""
         if path == os.path.join('html', 'test.html'):