diff --git a/frontends/etiquette_flask/backend/common.py b/frontends/etiquette_flask/backend/common.py
index 89879bb..04e4d83 100644
--- a/frontends/etiquette_flask/backend/common.py
+++ b/frontends/etiquette_flask/backend/common.py
@@ -65,7 +65,11 @@ def decorate_and_route(*route_args, **route_kwargs):
         # same one multiple times. The _fully_decorated will track that.
         if not hasattr(endpoint, '_fully_decorated'):
             endpoint = flasktools.ensure_response_type(endpoint)
-            endpoint = decorators.give_theme_cookie(endpoint)
+            endpoint = flasktools.give_theme_cookie(
+                endpoint,
+                cookie_name='etiquette_theme',
+                default_theme='slate',
+            )
             endpoint = decorators.catch_etiquette_exception(endpoint)
             endpoint = session_manager.give_token(endpoint)
 
diff --git a/frontends/etiquette_flask/backend/decorators.py b/frontends/etiquette_flask/backend/decorators.py
index 6dcf4b2..4257ec6 100644
--- a/frontends/etiquette_flask/backend/decorators.py
+++ b/frontends/etiquette_flask/backend/decorators.py
@@ -24,25 +24,3 @@ def catch_etiquette_exception(function):
             response = flasktools.json_response(response, status=status)
             flask.abort(response)
     return wrapped
-
-def give_theme_cookie(function):
-    @functools.wraps(function)
-    def wrapped(*args, **kwargs):
-        old_theme = request.cookies.get('etiquette_theme', None)
-        new_theme = request.args.get('theme', None)
-        theme = new_theme or old_theme or 'slate'
-
-        request.cookies = werkzeug.datastructures.MultiDict(request.cookies)
-        request.cookies['etiquette_theme'] = theme
-
-        response = function(*args, **kwargs)
-
-        if new_theme is None:
-            pass
-        elif new_theme == '':
-            response.set_cookie('etiquette_theme', value='', expires=0)
-        elif new_theme != old_theme:
-            response.set_cookie('etiquette_theme', value=new_theme, expires=2147483647)
-
-        return response
-    return wrapped