diff --git a/mongoengine/queryset/base.py b/mongoengine/queryset/base.py
index 9ea214cc..6c36d984 100644
--- a/mongoengine/queryset/base.py
+++ b/mongoengine/queryset/base.py
@@ -1872,8 +1872,8 @@ class BaseQuerySet(object):
             # Substitute the correct name for the field into the javascript
             return '.'.join([f.db_field for f in fields])
 
-        code = re.sub(u'\[\s*~([A-z_][A-z_0-9.]+?)\s*\]', field_sub, code)
-        code = re.sub(u'\{\{\s*~([A-z_][A-z_0-9.]+?)\s*\}\}', field_path_sub,
+        code = re.sub(r'\[\s*~([A-z_][A-z_0-9.]+?)\s*\]', field_sub, code)
+        code = re.sub(r'\{\{\s*~([A-z_][A-z_0-9.]+?)\s*\}\}', field_path_sub,
                       code)
         return code
 
diff --git a/setup.cfg b/setup.cfg
index fd6192b8..84086601 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -5,7 +5,7 @@ detailed-errors=1
 cover-package=mongoengine
 
 [flake8]
-ignore=E501,F401,F403,F405,I201,I202
+ignore=E501,F401,F403,F405,I201,I202,W504, W605
 exclude=build,dist,docs,venv,venv3,.tox,.eggs,tests
 max-complexity=47
 application-import-names=mongoengine,tests