diff --git a/polymorphic/compat.py b/polymorphic/compat.py
deleted file mode 100644
index ee7f1395..00000000
--- a/polymorphic/compat.py
+++ /dev/null
@@ -1,9 +0,0 @@
-"""Compatibility with Python 2 (taken from 'django.utils.six')"""
-
-
-def with_metaclass(meta, *bases):
-    class metaclass(type):
-        def __new__(cls, name, this_bases, d):
-            return meta(name, bases, d)
-
-    return type.__new__(metaclass, "temporary_class", (), {})
diff --git a/polymorphic/models.py b/polymorphic/models.py
index df0cc485..4a6cadce 100644
--- a/polymorphic/models.py
+++ b/polymorphic/models.py
@@ -6,8 +6,6 @@
 from django.db.models.fields.related import ForwardManyToOneDescriptor, ReverseOneToOneDescriptor
 from django.db.utils import DEFAULT_DB_ALIAS
 
-from polymorphic.compat import with_metaclass
-
 from .base import PolymorphicModelBase
 from .managers import PolymorphicManager
 from .query_translate import translate_polymorphic_Q_object
@@ -24,7 +22,7 @@ class PolymorphicTypeInvalid(RuntimeError):
     pass
 
 
-class PolymorphicModel(with_metaclass(PolymorphicModelBase, models.Model)):
+class PolymorphicModel(models.Model, metaclass=PolymorphicModelBase):
     """
     Abstract base class that provides polymorphic behaviour
     for any model directly or indirectly derived from it.
diff --git a/polymorphic/query_translate.py b/polymorphic/query_translate.py
index 627f1840..9e6a087a 100644
--- a/polymorphic/query_translate.py
+++ b/polymorphic/query_translate.py
@@ -38,7 +38,7 @@ def translate_polymorphic_filter_definitions_in_kwargs(
     Returns: a list of non-keyword-arguments (Q objects) to be added to the filter() query.
     """
     additional_args = []
-    for field_path, val in kwargs.copy().items():  # Python 3 needs copy
+    for field_path, val in kwargs.copy().items():  # `copy` so we're not mutating the dict
         new_expr = _translate_polymorphic_filter_definition(
             queryset_model, field_path, val, using=using
         )