diff --git a/mayan/apps/checkouts/managers.py b/mayan/apps/checkouts/managers.py
index 6d795729ce..a42fa7ba95 100644
--- a/mayan/apps/checkouts/managers.py
+++ b/mayan/apps/checkouts/managers.py
@@ -2,6 +2,7 @@ from __future__ import absolute_import, unicode_literals
 
 import logging
 
+from django.apps import apps
 from django.db import models
 from django.utils.timezone import now
 
@@ -88,6 +89,17 @@ class DocumentCheckoutManager(models.Manager):
         else:
             return not checkout_info.block_new_version
 
+    def get_by_natural_key(self, document_natural_key):
+        Document = apps.get_model(
+            app_label='documents', model_name='Document'
+        )
+        try:
+            document = Document.objects.get_by_natural_key(document_natural_key)
+        except Document.DoesNotExist:
+            raise self.model.DoesNotExist
+
+        return self.get(document__pk=document.pk)
+
 
 class NewVersionBlockManager(models.Manager):
     def block(self, document):
@@ -98,3 +110,14 @@ class NewVersionBlockManager(models.Manager):
 
     def is_blocked(self, document):
         return self.filter(document=document).exists()
+
+    def get_by_natural_key(self, document_natural_key):
+        Document = apps.get_model(
+            app_label='documents', model_name='Document'
+        )
+        try:
+            document = Document.objects.get_by_natural_key(document_natural_key)
+        except Document.DoesNotExist:
+            raise self.model.DoesNotExist
+
+        return self.get(document__pk=document.pk)
diff --git a/mayan/apps/checkouts/models.py b/mayan/apps/checkouts/models.py
index 2750fdf85f..43a38d8848 100644
--- a/mayan/apps/checkouts/models.py
+++ b/mayan/apps/checkouts/models.py
@@ -72,6 +72,10 @@ class DocumentCheckout(models.Model):
     def get_absolute_url(self):
         return reverse('checkout:checkout_info', args=(self.document.pk,))
 
+    def natural_key(self):
+        return self.document.natural_key()
+    natural_key.dependencies = ['documents.Document']
+
     def save(self, *args, **kwargs):
         # TODO: enclose in transaction
         new_checkout = not self.pk
@@ -104,3 +108,7 @@ class NewVersionBlock(models.Model):
     class Meta:
         verbose_name = _('New version block')
         verbose_name_plural = _('New version blocks')
+
+    def natural_key(self):
+        return self.document.natural_key()
+    natural_key.dependencies = ['documents.Document']