diff --git a/docs/changelog.rst b/docs/changelog.rst
index 0236d66..5fa72a7 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -1,6 +1,28 @@
 Changelog
 =========
 
+Version 1.3.1 (2018-04-16)
+--------------------------
+
+Backported various fixes from 2.x to support older Django versions:
+
+* Added ``PolymorphicTypeUndefined`` exception for incomplete imported models.
+  When a data migration or import creates an polymorphic model,
+  the ``polymorphic_ctype_id`` field should be filled in manually too.
+  The ``polymorphic.utils.reset_polymorphic_ctype`` function can be used for that.
+* Added ``PolymorphicTypeInvalid`` exception when database was incorrectly imported.
+* Added ``polymorphic.utils.get_base_polymorphic_model()`` to find the base model for types.
+* Using ``base_model`` on the polymorphic admins is no longer required, as this can be autodetected.
+* Fixed manager errors for swappable models.
+* Fixed ``deleteText`` of ``|as_script_options`` template filter.
+* Fixed ``.filter(applabel__ModelName___field=...)`` lookups.
+* Fixed proxy model support in formsets.
+* Fixed error with .defer and child models that use the same parent.
+* Fixed error message when ``polymorphic_ctype_id`` is null.
+* Fixed fieldsets recursion in the admin.
+* Improved ``polymorphic.utils.reset_polymorphic_ctype()`` to accept models in random ordering.
+
+
 Version 1.3 (2017-08-01)
 ------------------------
 
diff --git a/docs/conf.py b/docs/conf.py
index b9b053f..468deab 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -61,9 +61,9 @@ copyright = u'2013, Bert Constantin, Chris Glass, Diederik van der Boor'
 # built documents.
 #
 # The short X.Y version.
-version = '1.3'
+version = '1.3.1'
 # The full version, including alpha/beta/rc tags.
-release = '1.3'
+release = '1.3.1'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/polymorphic/__init__.py b/polymorphic/__init__.py
index 77d7fe2..714ff51 100644
--- a/polymorphic/__init__.py
+++ b/polymorphic/__init__.py
@@ -8,4 +8,4 @@ Please see LICENSE and AUTHORS for more information.
 """
 
 # See PEP 440 (https://www.python.org/dev/peps/pep-0440/)
-__version__ = "1.3"
+__version__ = "1.3.1"