diff --git a/requirements/tests.txt b/requirements/tests.txt
index 522b1b2..c425c50 100644
--- a/requirements/tests.txt
+++ b/requirements/tests.txt
@@ -1,3 +1,6 @@
+django>=2.2.16,<3.0
+URLObject
+django-appconf
 docutils
 model_mommy
 django-ttag>=2.3
diff --git a/setup.py b/setup.py
index fe03807..911c7b3 100644
--- a/setup.py
+++ b/setup.py
@@ -37,16 +37,11 @@ def find_version(*file_paths):
         "Development Status :: 4 - Beta",
         'Environment :: Web Environment',
         'Framework :: Django',
-        'Framework :: Django :: 1.9',
-        'Framework :: Django :: 1.10',
-        'Framework :: Django :: 1.11',
+        'Framework :: Django :: 2.2',
         'Intended Audience :: Developers',
         'License :: OSI Approved :: BSD License',
         'Operating System :: OS Independent',
-        'Programming Language :: Python',
-        'Programming Language :: Python :: 2.5',
-        'Programming Language :: Python :: 2.6',
-        'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3.8',
         'Topic :: Utilities',
     ],
     install_requires=[
diff --git a/sorter/__init__.py b/sorter/__init__.py
index 1878d2d..2930230 100644
--- a/sorter/__init__.py
+++ b/sorter/__init__.py
@@ -1 +1 @@
-__version__ = "0.3-caktus"
+__version__ = "0.4-caktus"
diff --git a/sorter/templatetags/sorter_tags.py b/sorter/templatetags/sorter_tags.py
index 19b6642..a3668b0 100644
--- a/sorter/templatetags/sorter_tags.py
+++ b/sorter/templatetags/sorter_tags.py
@@ -32,7 +32,7 @@ def clean_with(self, value):
         """
         Cleans the given name of the sort query
         """
-        if not isinstance(value, basestring):
+        if not isinstance(value, str):
             raise TemplateSyntaxError("Value '%s' is not a string" % value)
         # in case the value equals the default query name
         # or it already has the default query name prefixed
@@ -90,7 +90,7 @@ class TemplateAsTagMetaclass(ttag.helpers.as_tag.AsTagMetaclass):
     options_class = TemplateAsTagOptions
 
 
-class SortURL(SorterAsTag):
+class SortURL(SorterAsTag, metaclass=TemplateAsTagMetaclass):
     """
     Parses a tag that's supposed to be in this format:
 
@@ -99,8 +99,6 @@ class SortURL(SorterAsTag):
     {% sorturl with "objects" by "creation_date,-title" %}
 
     """
-    __metaclass__ = TemplateAsTagMetaclass
-
     with_ = ttag.Arg(required=False, named=True, default=settings.SORTER_DEFAULT_QUERY_NAME)
     rel = ttag.Arg(required=False, named=True)
     class_ = ttag.Arg(required=False, named=True)
diff --git a/sorter/test_settings.py b/sorter/test_settings.py
index 2f3a9f8..7ab490e 100644
--- a/sorter/test_settings.py
+++ b/sorter/test_settings.py
@@ -12,9 +12,16 @@
     'django.contrib.sites',
     'django.contrib.auth',
     'django.contrib.admin',
+    'django.contrib.messages',
     'sorter',
 ]
 
+MIDDLEWARE = [
+    'django.contrib.auth.middleware.AuthenticationMiddleware',
+    'django.contrib.messages.middleware.MessageMiddleware',
+    'django.contrib.sessions.middleware.SessionMiddleware',
+]
+
 TEMPLATES = [
     {
         'BACKEND': 'django.template.backends.django.DjangoTemplates',
@@ -22,6 +29,7 @@
         'OPTIONS': {
             'context_processors': (
                 "django.contrib.auth.context_processors.auth",
+                'django.contrib.messages.context_processors.messages'
             ),
             'builtins': [
                 'sorter.templatetags.sorter_tags',
diff --git a/sorter/utils.py b/sorter/utils.py
index 3ca7cc3..9ebc3c3 100644
--- a/sorter/utils.py
+++ b/sorter/utils.py
@@ -1,4 +1,4 @@
-from itertools import tee, izip, chain
+from itertools import tee, chain
 
 
 def cycle_pairs(iterable):
@@ -9,5 +9,5 @@ def cycle_pairs(iterable):
     """
     first, last = iterable[0], iterable[-1]
     a, b = tee(iterable)
-    iter(b).next()
-    return chain(izip(a, b), [(last, first)])
+    next(iter(b))
+    return chain(zip(a, b), [(last, first)])