diff --git a/django/utils/encoding.py b/django/utils/encoding.py
index 4e347bdc5f6..48fde393a71 100644
--- a/django/utils/encoding.py
+++ b/django/utils/encoding.py
@@ -25,22 +25,8 @@ class DjangoUnicodeDecodeError(UnicodeDecodeError):
                 type(self.obj))
 
 
-def python_2_unicode_compatible(klass):
-    """
-    A decorator that defines __unicode__ and __str__ methods under Python 2.
-    Under Python 3 it does nothing.
-
-    To support Python 2 and 3 with a single code base, define a __str__ method
-    returning text and apply this decorator to the class.
-    """
-    if six.PY2:
-        if '__str__' not in klass.__dict__:
-            raise ValueError("@python_2_unicode_compatible cannot be applied "
-                             "to %s because it doesn't define __str__()." %
-                             klass.__name__)
-        klass.__unicode__ = klass.__str__
-        klass.__str__ = lambda self: self.__unicode__().encode('utf-8')
-    return klass
+# For backwards compatibility. (originally in Django, then added to six 1.9)
+python_2_unicode_compatible = six.python_2_unicode_compatible
 
 
 def smart_text(s, encoding='utf-8', strings_only=False, errors='strict'):