diff --git a/mayan/apps/acls/models.py b/mayan/apps/acls/models.py
index 2f36366b47..171938c8be 100644
--- a/mayan/apps/acls/models.py
+++ b/mayan/apps/acls/models.py
@@ -30,8 +30,8 @@ class AccessControlList(models.Model):
     in the Setup menu.
     """
     content_type = models.ForeignKey(
-        ContentType, on_delete=models.CASCADE,
-        related_name='object_content_type'
+        on_delete=models.CASCADE, related_name='object_content_type',
+        to=ContentType
     )
     object_id = models.PositiveIntegerField()
     content_object = GenericForeignKey(
@@ -39,11 +39,11 @@ class AccessControlList(models.Model):
     )
     # TODO: limit choices to the permissions valid for the content_object
     permissions = models.ManyToManyField(
-        StoredPermission, blank=True, related_name='acls',
+        blank=True, related_name='acls', to=StoredPermission,
         verbose_name=_('Permissions')
     )
     role = models.ForeignKey(
-        Role, on_delete=models.CASCADE, related_name='acls',
+        on_delete=models.CASCADE, related_name='acls', to=Role,
         verbose_name=_('Role')
     )
 
diff --git a/mayan/apps/cabinets/models.py b/mayan/apps/cabinets/models.py
index d2d54598e6..014d304285 100644
--- a/mayan/apps/cabinets/models.py
+++ b/mayan/apps/cabinets/models.py
@@ -20,12 +20,12 @@ from .search import cabinet_search  # NOQA
 @python_2_unicode_compatible
 class Cabinet(MPTTModel):
     parent = TreeForeignKey(
-        'self', blank=True, db_index=True, null=True,
-        on_delete=models.CASCADE, related_name='children'
+        blank=True, db_index=True, null=True, on_delete=models.CASCADE,
+        related_name='children', to='self'
     )
     label = models.CharField(max_length=128, verbose_name=_('Label'))
     documents = models.ManyToManyField(
-        Document, blank=True, related_name='cabinets',
+        blank=True, related_name='cabinets', to=Document,
         verbose_name=_('Documents')
     )
 
diff --git a/mayan/apps/checkouts/models.py b/mayan/apps/checkouts/models.py
index 4d9eba9e67..2750fdf85f 100644
--- a/mayan/apps/checkouts/models.py
+++ b/mayan/apps/checkouts/models.py
@@ -25,7 +25,7 @@ class DocumentCheckout(models.Model):
     Model to store the state and information of a document checkout
     """
     document = models.OneToOneField(
-        Document, on_delete=models.CASCADE, verbose_name=_('Document')
+        on_delete=models.CASCADE, to=Document, verbose_name=_('Document')
     )
     checkout_datetime = models.DateTimeField(
         auto_now_add=True, verbose_name=_('Check out date and time')
@@ -37,7 +37,7 @@ class DocumentCheckout(models.Model):
         verbose_name=_('Check out expiration date and time')
     )
     user = models.ForeignKey(
-        settings.AUTH_USER_MODEL, on_delete=models.CASCADE,
+        on_delete=models.CASCADE, to=settings.AUTH_USER_MODEL,
         verbose_name=_('User')
     )
     block_new_version = models.BooleanField(
@@ -96,7 +96,7 @@ class DocumentCheckout(models.Model):
 
 class NewVersionBlock(models.Model):
     document = models.ForeignKey(
-        Document, on_delete=models.CASCADE, verbose_name=_('Document')
+        on_delete=models.CASCADE, to=Document, verbose_name=_('Document')
     )
 
     objects = NewVersionBlockManager()
diff --git a/mayan/apps/common/models.py b/mayan/apps/common/models.py
index a892bce1d3..5d75ff363b 100644
--- a/mayan/apps/common/models.py
+++ b/mayan/apps/common/models.py
@@ -24,8 +24,8 @@ class ErrorLogEntry(models.Model):
         max_length=128, verbose_name=_('Namespace')
     )
     content_type = models.ForeignKey(
-        ContentType, blank=True, on_delete=models.CASCADE, null=True,
-        related_name='error_log_content_type'
+        blank=True, on_delete=models.CASCADE, null=True,
+        related_name='error_log_content_type', to=ContentType,
     )
     object_id = models.PositiveIntegerField(blank=True, null=True)
     content_object = GenericForeignKey(
@@ -77,8 +77,8 @@ class SharedUploadedFile(models.Model):
 @python_2_unicode_compatible
 class UserLocaleProfile(models.Model):
     user = models.OneToOneField(
-        settings.AUTH_USER_MODEL, on_delete=models.CASCADE,
-        related_name='locale_profile', verbose_name=_('User')
+        on_delete=models.CASCADE, related_name='locale_profile',
+        to=settings.AUTH_USER_MODEL, verbose_name=_('User')
     )
     timezone = models.CharField(
         choices=zip(common_timezones, common_timezones), max_length=48,
diff --git a/mayan/apps/converter/models.py b/mayan/apps/converter/models.py
index 909a8ea718..73df0efade 100644
--- a/mayan/apps/converter/models.py
+++ b/mayan/apps/converter/models.py
@@ -29,10 +29,9 @@ class Transformation(models.Model):
     transformation argument. Example: if a page is rotated with the Rotation
     transformation, this field will show by how many degrees it was rotated.
     """
-    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
+    content_type = models.ForeignKey(on_delete=models.CASCADE, to=ContentType)
     object_id = models.PositiveIntegerField()
     content_object = GenericForeignKey('content_type', 'object_id')
-
     order = models.PositiveIntegerField(
         blank=True, db_index=True, default=0, help_text=_(
             'Order in which the transformations will be executed. If left '
diff --git a/mayan/apps/django_gpg/models.py b/mayan/apps/django_gpg/models.py
index 050f587280..5569ee692a 100644
--- a/mayan/apps/django_gpg/models.py
+++ b/mayan/apps/django_gpg/models.py
@@ -76,6 +76,10 @@ class Key(models.Model):
     def get_absolute_url(self):
         return reverse('django_gpg:key_detail', args=(self.pk,))
 
+    @property
+    def key_id(self):
+        return self.fingerprint[-8:]
+
     def save(self, *args, **kwargs):
         import_results, key_info = gpg_backend.import_and_list_keys(
             key_data=self.key_data
@@ -119,7 +123,3 @@ class Key(models.Model):
                 raise NeedPassphrase
 
         return file_sign_results
-
-    @property
-    def key_id(self):
-        return self.fingerprint[-8:]
diff --git a/mayan/apps/document_comments/models.py b/mayan/apps/document_comments/models.py
index c2e81a7db3..016591aae2 100644
--- a/mayan/apps/document_comments/models.py
+++ b/mayan/apps/document_comments/models.py
@@ -19,12 +19,12 @@ logger = logging.getLogger(__name__)
 @python_2_unicode_compatible
 class Comment(models.Model):
     document = models.ForeignKey(
-        Document, db_index=True, on_delete=models.CASCADE,
-        related_name='comments', verbose_name=_('Document')
+        db_index=True, on_delete=models.CASCADE, related_name='comments',
+        to=Document, verbose_name=_('Document')
     )
     user = models.ForeignKey(
-        settings.AUTH_USER_MODEL, editable=False, on_delete=models.CASCADE,
-        related_name='comments', verbose_name=_('User'),
+        editable=False, on_delete=models.CASCADE, related_name='comments',
+        to=settings.AUTH_USER_MODEL, verbose_name=_('User'),
     )
     # Translators: Comment here is a noun and refers to the actual text stored
     comment = models.TextField(verbose_name=_('Comment'))
diff --git a/mayan/apps/document_indexing/models.py b/mayan/apps/document_indexing/models.py
index 63948d30cf..78ef2ff4bc 100644
--- a/mayan/apps/document_indexing/models.py
+++ b/mayan/apps/document_indexing/models.py
@@ -46,7 +46,7 @@ class Index(models.Model):
         verbose_name=_('Enabled')
     )
     document_types = models.ManyToManyField(
-        DocumentType, verbose_name=_('Document types')
+        to=DocumentType, verbose_name=_('Document types')
     )
 
     objects = IndexManager()
@@ -146,10 +146,10 @@ class IndexTemplateNode(MPTTModel):
     documents but not both.
     """
     parent = TreeForeignKey(
-        'self', blank=True, null=True, on_delete=models.CASCADE
+        blank=True, null=True, on_delete=models.CASCADE, to='self',
     )
     index = models.ForeignKey(
-        Index, on_delete=models.CASCADE, related_name='node_templates',
+        on_delete=models.CASCADE, related_name='node_templates', to=Index,
         verbose_name=_('Index')
     )
     expression = models.TextField(
@@ -276,18 +276,17 @@ class IndexTemplateNode(MPTTModel):
 @python_2_unicode_compatible
 class IndexInstanceNode(MPTTModel):
     parent = TreeForeignKey(
-        'self', blank=True, null=True, on_delete=models.CASCADE
+        blank=True, null=True, on_delete=models.CASCADE, to='self',
     )
     index_template_node = models.ForeignKey(
-        IndexTemplateNode, on_delete=models.CASCADE,
-        related_name='index_instance_nodes',
-        verbose_name=_('Index template node')
+        on_delete=models.CASCADE, related_name='index_instance_nodes',
+        to=IndexTemplateNode, verbose_name=_('Index template node')
     )
     value = models.CharField(
         blank=True, db_index=True, max_length=128, verbose_name=_('Value')
     )
     documents = models.ManyToManyField(
-        Document, related_name='index_instance_nodes',
+        related_name='index_instance_nodes', to=Document,
         verbose_name=_('Documents')
     )
 
diff --git a/mayan/apps/document_parsing/models.py b/mayan/apps/document_parsing/models.py
index d631da9ad0..23fae82a96 100644
--- a/mayan/apps/document_parsing/models.py
+++ b/mayan/apps/document_parsing/models.py
@@ -12,7 +12,7 @@ from .managers import DocumentPageContentManager
 @python_2_unicode_compatible
 class DocumentPageContent(models.Model):
     document_page = models.OneToOneField(
-        DocumentPage, on_delete=models.CASCADE, related_name='content',
+        on_delete=models.CASCADE, related_name='content', to=DocumentPage,
         verbose_name=_('Document page')
     )
     content = models.TextField(blank=True, verbose_name=_('Content'))
@@ -30,8 +30,8 @@ class DocumentPageContent(models.Model):
 @python_2_unicode_compatible
 class DocumentVersionParseError(models.Model):
     document_version = models.ForeignKey(
-        DocumentVersion, on_delete=models.CASCADE,
-        related_name='parsing_errors', verbose_name=_('Document version')
+        on_delete=models.CASCADE, related_name='parsing_errors',
+        to=DocumentVersion, verbose_name=_('Document version')
     )
     datetime_submitted = models.DateTimeField(
         auto_now_add=True, db_index=True, verbose_name=_('Date time submitted')
diff --git a/mayan/apps/document_signatures/models.py b/mayan/apps/document_signatures/models.py
index 65dd50e447..17d1b6bb9d 100644
--- a/mayan/apps/document_signatures/models.py
+++ b/mayan/apps/document_signatures/models.py
@@ -36,8 +36,8 @@ class SignatureBaseModel(models.Model):
     even when using the same key.
     """
     document_version = models.ForeignKey(
-        DocumentVersion, editable=False, on_delete=models.CASCADE,
-        related_name='signatures', verbose_name=_('Document version')
+        editable=False, on_delete=models.CASCADE, related_name='signatures',
+        to=DocumentVersion, verbose_name=_('Document version')
     )
     # Basic fields
     date = models.DateField(
diff --git a/mayan/apps/document_states/models.py b/mayan/apps/document_states/models.py
index 25fb520362..5fbbaf6049 100644
--- a/mayan/apps/document_states/models.py
+++ b/mayan/apps/document_states/models.py
@@ -47,8 +47,9 @@ class Workflow(models.Model):
         max_length=255, unique=True, verbose_name=_('Label')
     )
     document_types = models.ManyToManyField(
-        DocumentType, related_name='workflows',
-        verbose_name=_('Document types')
+        related_name='workflows', to=DocumentType, verbose_name=_(
+            'Document types'
+        )
     )
 
     objects = WorkflowManager()
@@ -141,7 +142,7 @@ class WorkflowState(models.Model):
     the Completion Amount will show 66%.
     """
     workflow = models.ForeignKey(
-        Workflow, on_delete=models.CASCADE, related_name='states',
+        on_delete=models.CASCADE, related_name='states', to=Workflow,
         verbose_name=_('Workflow')
     )
     label = models.CharField(max_length=255, verbose_name=_('Label'))
@@ -210,8 +211,8 @@ class WorkflowState(models.Model):
 @python_2_unicode_compatible
 class WorkflowStateAction(models.Model):
     state = models.ForeignKey(
-        WorkflowState, on_delete=models.CASCADE,
-        related_name='actions', verbose_name=_('Workflow state')
+        on_delete=models.CASCADE, related_name='actions', to=WorkflowState,
+        verbose_name=_('Workflow state')
     )
     label = models.CharField(max_length=255, verbose_name=_('Label'))
     enabled = models.BooleanField(default=True, verbose_name=_('Enabled'))
@@ -272,18 +273,17 @@ class WorkflowStateAction(models.Model):
 @python_2_unicode_compatible
 class WorkflowTransition(models.Model):
     workflow = models.ForeignKey(
-        Workflow, on_delete=models.CASCADE, related_name='transitions',
+        on_delete=models.CASCADE, related_name='transitions', to=Workflow,
         verbose_name=_('Workflow')
     )
     label = models.CharField(max_length=255, verbose_name=_('Label'))
     origin_state = models.ForeignKey(
-        WorkflowState, on_delete=models.CASCADE,
-        related_name='origin_transitions', verbose_name=_('Origin state')
+        on_delete=models.CASCADE, related_name='origin_transitions',
+        to=WorkflowState, verbose_name=_('Origin state')
     )
     destination_state = models.ForeignKey(
-        WorkflowState, on_delete=models.CASCADE,
-        related_name='destination_transitions',
-        verbose_name=_('Destination state')
+        on_delete=models.CASCADE, related_name='destination_transitions',
+        to=WorkflowState, verbose_name=_('Destination state')
     )
 
     class Meta:
@@ -301,11 +301,11 @@ class WorkflowTransition(models.Model):
 @python_2_unicode_compatible
 class WorkflowTransitionTriggerEvent(models.Model):
     transition = models.ForeignKey(
-        WorkflowTransition, on_delete=models.CASCADE,
-        related_name='trigger_events', verbose_name=_('Transition')
+        on_delete=models.CASCADE, related_name='trigger_events',
+        to=WorkflowTransition, verbose_name=_('Transition')
     )
     event_type = models.ForeignKey(
-        StoredEventType, on_delete=models.CASCADE,
+        on_delete=models.CASCADE, to=StoredEventType,
         verbose_name=_('Event type')
     )
 
@@ -320,11 +320,11 @@ class WorkflowTransitionTriggerEvent(models.Model):
 @python_2_unicode_compatible
 class WorkflowInstance(models.Model):
     workflow = models.ForeignKey(
-        Workflow, on_delete=models.CASCADE, related_name='instances',
+        on_delete=models.CASCADE, related_name='instances', to=Workflow,
         verbose_name=_('Workflow')
     )
     document = models.ForeignKey(
-        Document, on_delete=models.CASCADE, related_name='workflows',
+        on_delete=models.CASCADE, related_name='workflows', to=Document,
         verbose_name=_('Document')
     )
 
@@ -425,19 +425,19 @@ class WorkflowInstanceLogEntry(models.Model):
     the document state to the Actual state.
     """
     workflow_instance = models.ForeignKey(
-        WorkflowInstance, on_delete=models.CASCADE,
-        related_name='log_entries', verbose_name=_('Workflow instance')
+        on_delete=models.CASCADE, related_name='log_entries',
+        to=WorkflowInstance, verbose_name=_('Workflow instance')
     )
     datetime = models.DateTimeField(
         auto_now_add=True, db_index=True, verbose_name=_('Datetime')
     )
     transition = models.ForeignKey(
-        WorkflowTransition, on_delete=models.CASCADE,
+        on_delete=models.CASCADE, to=WorkflowTransition,
         verbose_name=_('Transition')
     )
     user = models.ForeignKey(
-        settings.AUTH_USER_MODEL, blank=True, null=True,
-        on_delete=models.CASCADE, verbose_name=_('User')
+        blank=True, null=True, on_delete=models.CASCADE,
+        to=settings.AUTH_USER_MODEL, verbose_name=_('User')
     )
     comment = models.TextField(blank=True, verbose_name=_('Comment'))
 
diff --git a/mayan/apps/documents/models.py b/mayan/apps/documents/models.py
index 400284e839..cb34fc233f 100644
--- a/mayan/apps/documents/models.py
+++ b/mayan/apps/documents/models.py
@@ -156,7 +156,7 @@ class Document(models.Model):
     """
     uuid = models.UUIDField(default=uuid.uuid4, editable=False)
     document_type = models.ForeignKey(
-        DocumentType, on_delete=models.CASCADE, related_name='documents',
+        on_delete=models.CASCADE, related_name='documents', to=DocumentType,
         verbose_name=_('Document type')
     )
     label = models.CharField(
@@ -381,7 +381,7 @@ class DocumentVersion(models.Model):
         cls._post_save_hooks[order] = func
 
     document = models.ForeignKey(
-        Document, on_delete=models.CASCADE, related_name='versions',
+        on_delete=models.CASCADE, related_name='versions', to=Document,
         verbose_name=_('Document')
     )
     timestamp = models.DateTimeField(
@@ -455,6 +455,37 @@ class DocumentVersion(models.Model):
         else:
             return '#'
 
+    def get_intermidiate_file(self):
+        cache_filename = self.cache_filename
+        logger.debug('Intermidiate filename: %s', cache_filename)
+
+        if cache_storage_backend.exists(cache_filename):
+            logger.debug('Intermidiate file "%s" found.', cache_filename)
+
+            return cache_storage_backend.open(cache_filename)
+        else:
+            logger.debug('Intermidiate file "%s" not found.', cache_filename)
+
+            try:
+                converter = converter_class(file_object=self.open())
+                pdf_file_object = converter.to_pdf()
+
+                with cache_storage_backend.open(cache_filename, 'wb+') as file_object:
+                    for chunk in pdf_file_object:
+                        file_object.write(chunk)
+
+                return cache_storage_backend.open(cache_filename)
+            except InvalidOfficeFormat:
+                return self.open()
+            except Exception as exception:
+                # Cleanup in case of error
+                logger.error(
+                    'Error creating intermediate file "%s"; %s.',
+                    cache_filename, exception
+                )
+                cache_storage_backend.delete(cache_filename)
+                raise
+
     def get_rendered_string(self, preserve_extension=False):
         if preserve_extension:
             filename, extension = os.path.splitext(self.document.label)
@@ -471,6 +502,47 @@ class DocumentVersion(models.Model):
             context=Context({'instance': self})
         )
 
+    def invalidate_cache(self):
+        cache_storage_backend.delete(self.cache_filename)
+        for page in self.pages.all():
+            page.invalidate_cache()
+
+    def open(self, raw=False):
+        """
+        Return a file descriptor to a document version's file irrespective of
+        the storage backend
+        """
+        if raw:
+            return self.file.storage.open(self.file.name)
+        else:
+            result = self.file.storage.open(self.file.name)
+            for key in sorted(DocumentVersion._pre_open_hooks):
+                result = DocumentVersion._pre_open_hooks[key](
+                    file_object=result, document_version=self
+                )
+
+            return result
+
+    @property
+    def page_count(self):
+        """
+        The number of pages that the document posses.
+        """
+        return self.pages.count()
+
+    def revert(self, _user=None):
+        """
+        Delete the subsequent versions after this one
+        """
+        logger.info(
+            'Reverting to document document: %s to version: %s',
+            self.document, self
+        )
+
+        event_document_version_revert.commit(actor=_user, target=self.document)
+        for version in self.document.versions.filter(timestamp__gt=self.timestamp):
+            version.delete()
+
     def save(self, *args, **kwargs):
         """
         Overloaded save method that updates the document version's checksum,
@@ -527,78 +599,6 @@ class DocumentVersion(models.Model):
                         sender=Document, instance=self.document
                     )
 
-    def get_intermidiate_file(self):
-        cache_filename = self.cache_filename
-        logger.debug('Intermidiate filename: %s', cache_filename)
-
-        if cache_storage_backend.exists(cache_filename):
-            logger.debug('Intermidiate file "%s" found.', cache_filename)
-
-            return cache_storage_backend.open(cache_filename)
-        else:
-            logger.debug('Intermidiate file "%s" not found.', cache_filename)
-
-            try:
-                converter = converter_class(file_object=self.open())
-                pdf_file_object = converter.to_pdf()
-
-                with cache_storage_backend.open(cache_filename, 'wb+') as file_object:
-                    for chunk in pdf_file_object:
-                        file_object.write(chunk)
-
-                return cache_storage_backend.open(cache_filename)
-            except InvalidOfficeFormat:
-                return self.open()
-            except Exception as exception:
-                # Cleanup in case of error
-                logger.error(
-                    'Error creating intermediate file "%s"; %s.',
-                    cache_filename, exception
-                )
-                cache_storage_backend.delete(cache_filename)
-                raise
-
-    def invalidate_cache(self):
-        cache_storage_backend.delete(self.cache_filename)
-        for page in self.pages.all():
-            page.invalidate_cache()
-
-    def open(self, raw=False):
-        """
-        Return a file descriptor to a document version's file irrespective of
-        the storage backend
-        """
-        if raw:
-            return self.file.storage.open(self.file.name)
-        else:
-            result = self.file.storage.open(self.file.name)
-            for key in sorted(DocumentVersion._pre_open_hooks):
-                result = DocumentVersion._pre_open_hooks[key](
-                    file_object=result, document_version=self
-                )
-
-            return result
-
-    @property
-    def page_count(self):
-        """
-        The number of pages that the document posses.
-        """
-        return self.pages.count()
-
-    def revert(self, _user=None):
-        """
-        Delete the subsequent versions after this one
-        """
-        logger.info(
-            'Reverting to document document: %s to version: %s',
-            self.document, self
-        )
-
-        event_document_version_revert.commit(actor=_user, target=self.document)
-        for version in self.document.versions.filter(timestamp__gt=self.timestamp):
-            version.delete()
-
     def save_to_file(self, filepath, buffer_size=1024 * 1024):
         """
         Save a copy of the document from the document storage backend
@@ -692,7 +692,7 @@ class DocumentTypeFilename(models.Model):
     quick rename functionality
     """
     document_type = models.ForeignKey(
-        DocumentType, on_delete=models.CASCADE, related_name='filenames',
+        on_delete=models.CASCADE, related_name='filenames', to=DocumentType,
         verbose_name=_('Document type')
     )
     filename = models.CharField(
@@ -716,7 +716,7 @@ class DocumentPage(models.Model):
     Model that describes a document version page
     """
     document_version = models.ForeignKey(
-        DocumentVersion, on_delete=models.CASCADE, related_name='pages',
+        on_delete=models.CASCADE, related_name='pages', to=DocumentVersion,
         verbose_name=_('Document version')
     )
     page_number = models.PositiveIntegerField(
@@ -895,8 +895,8 @@ class DocumentPage(models.Model):
 
 class DocumentPageCachedImage(models.Model):
     document_page = models.ForeignKey(
-        DocumentPage, on_delete=models.CASCADE, related_name='cached_images',
-        verbose_name=_('Document page')
+        on_delete=models.CASCADE, related_name='cached_images',
+        to=DocumentPage, verbose_name=_('Document page')
     )
     filename = models.CharField(max_length=128, verbose_name=_('Filename'))
 
@@ -924,11 +924,11 @@ class RecentDocument(models.Model):
     a given user
     """
     user = models.ForeignKey(
-        settings.AUTH_USER_MODEL, db_index=True, editable=False,
-        on_delete=models.CASCADE, verbose_name=_('User')
+        db_index=True, editable=False, on_delete=models.CASCADE,
+        to=settings.AUTH_USER_MODEL, verbose_name=_('User')
     )
     document = models.ForeignKey(
-        Document, editable=False, on_delete=models.CASCADE,
+        editable=False, on_delete=models.CASCADE, to=Document,
         verbose_name=_('Document')
     )
     datetime_accessed = models.DateTimeField(
@@ -953,11 +953,11 @@ class RecentDocument(models.Model):
 @python_2_unicode_compatible
 class DuplicatedDocument(models.Model):
     document = models.ForeignKey(
-        Document, on_delete=models.CASCADE, related_name='duplicates',
+        on_delete=models.CASCADE, related_name='duplicates', to=Document,
         verbose_name=_('Document')
     )
     documents = models.ManyToManyField(
-        Document, verbose_name=_('Duplicated documents')
+        to=Document, verbose_name=_('Duplicated documents')
     )
     datetime_added = models.DateTimeField(
         auto_now_add=True, db_index=True, verbose_name=_('Added')
diff --git a/mayan/apps/events/models.py b/mayan/apps/events/models.py
index 1a8ae597fe..565c5e21d8 100644
--- a/mayan/apps/events/models.py
+++ b/mayan/apps/events/models.py
@@ -43,12 +43,13 @@ class StoredEventType(models.Model):
 @python_2_unicode_compatible
 class EventSubscription(models.Model):
     user = models.ForeignKey(
-        settings.AUTH_USER_MODEL, db_index=True, on_delete=models.CASCADE,
-        related_name='event_subscriptions', verbose_name=_('User')
+        db_index=True, on_delete=models.CASCADE,
+        related_name='event_subscriptions', to=settings.AUTH_USER_MODEL,
+        verbose_name=_('User')
     )
     stored_event_type = models.ForeignKey(
-        StoredEventType, on_delete=models.CASCADE,
-        related_name='event_subscriptions', verbose_name=_('Event type')
+        on_delete=models.CASCADE, related_name='event_subscriptions',
+        to=StoredEventType, verbose_name=_('Event type')
     )
 
     objects = EventSubscriptionManager()
@@ -64,11 +65,12 @@ class EventSubscription(models.Model):
 @python_2_unicode_compatible
 class Notification(models.Model):
     user = models.ForeignKey(
-        settings.AUTH_USER_MODEL, db_index=True, on_delete=models.CASCADE,
-        related_name='notifications', verbose_name=_('User')
+        db_index=True, on_delete=models.CASCADE,
+        related_name='notifications', to=settings.AUTH_USER_MODEL,
+        verbose_name=_('User')
     )
     action = models.ForeignKey(
-        Action, on_delete=models.CASCADE, related_name='notifications',
+        on_delete=models.CASCADE, related_name='notifications', to=Action,
         verbose_name=_('Action')
     )
     read = models.BooleanField(default=False, verbose_name=_('Read'))
@@ -85,7 +87,7 @@ class Notification(models.Model):
 @python_2_unicode_compatible
 class ObjectEventSubscription(models.Model):
     content_type = models.ForeignKey(
-        ContentType, on_delete=models.CASCADE,
+        on_delete=models.CASCADE, to=ContentType,
     )
     object_id = models.PositiveIntegerField()
     content_object = GenericForeignKey(
@@ -93,12 +95,13 @@ class ObjectEventSubscription(models.Model):
         fk_field='object_id',
     )
     user = models.ForeignKey(
-        settings.AUTH_USER_MODEL, db_index=True, on_delete=models.CASCADE,
-        related_name='object_subscriptions', verbose_name=_('User')
+        db_index=True, on_delete=models.CASCADE,
+        related_name='object_subscriptions', to=settings.AUTH_USER_MODEL,
+        verbose_name=_('User')
     )
     stored_event_type = models.ForeignKey(
-        StoredEventType, on_delete=models.CASCADE,
-        related_name='object_subscriptions', verbose_name=_('Event type')
+        on_delete=models.CASCADE, related_name='object_subscriptions',
+        to=StoredEventType, verbose_name=_('Event type')
     )
 
     objects = ObjectEventSubscriptionManager()
diff --git a/mayan/apps/linking/models.py b/mayan/apps/linking/models.py
index beb9acd90a..e2e805f212 100644
--- a/mayan/apps/linking/models.py
+++ b/mayan/apps/linking/models.py
@@ -29,7 +29,7 @@ class SmartLink(models.Model):
     )
     enabled = models.BooleanField(default=True, verbose_name=_('Enabled'))
     document_types = models.ManyToManyField(
-        DocumentType, verbose_name=_('Document types')
+        to=DocumentType, verbose_name=_('Document types')
     )
 
     objects = SmartLinkManager()
@@ -105,7 +105,7 @@ class ResolvedSmartLink(SmartLink):
 @python_2_unicode_compatible
 class SmartLinkCondition(models.Model):
     smart_link = models.ForeignKey(
-        SmartLink, on_delete=models.CASCADE, related_name='conditions',
+        on_delete=models.CASCADE, related_name='conditions', to=SmartLink,
         verbose_name=_('Smart link')
     )
     inclusion = models.CharField(
diff --git a/mayan/apps/mailer/models.py b/mayan/apps/mailer/models.py
index 0b7eaebfb6..d2d8aca45b 100644
--- a/mayan/apps/mailer/models.py
+++ b/mayan/apps/mailer/models.py
@@ -111,7 +111,7 @@ class UserMailer(models.Model):
 
 class UserMailerLogEntry(models.Model):
     user_mailer = models.ForeignKey(
-        UserMailer, on_delete=models.CASCADE, related_name='error_log',
+        on_delete=models.CASCADE, related_name='error_log', to=UserMailer,
         verbose_name=_('User mailer')
     )
     datetime = models.DateTimeField(
diff --git a/mayan/apps/metadata/models.py b/mayan/apps/metadata/models.py
index d7097bef4e..b7e5a21503 100644
--- a/mayan/apps/metadata/models.py
+++ b/mayan/apps/metadata/models.py
@@ -149,11 +149,11 @@ class DocumentMetadata(models.Model):
     current value
     """
     document = models.ForeignKey(
-        Document, on_delete=models.CASCADE, related_name='metadata',
+        on_delete=models.CASCADE, related_name='metadata', to=Document,
         verbose_name=_('Document')
     )
     metadata_type = models.ForeignKey(
-        MetadataType, on_delete=models.CASCADE, verbose_name=_('Type')
+        on_delete=models.CASCADE, to=MetadataType, verbose_name=_('Type')
     )
     value = models.CharField(
         blank=True, db_index=True, max_length=255, null=True,
@@ -207,11 +207,11 @@ class DocumentMetadata(models.Model):
 @python_2_unicode_compatible
 class DocumentTypeMetadataType(models.Model):
     document_type = models.ForeignKey(
-        DocumentType, on_delete=models.CASCADE, related_name='metadata',
+        on_delete=models.CASCADE, related_name='metadata', to=DocumentType,
         verbose_name=_('Document type')
     )
     metadata_type = models.ForeignKey(
-        MetadataType, on_delete=models.CASCADE,
+        on_delete=models.CASCADE, to=MetadataType,
         verbose_name=_('Metadata type')
     )
     required = models.BooleanField(default=False, verbose_name=_('Required'))
diff --git a/mayan/apps/ocr/models.py b/mayan/apps/ocr/models.py
index b82641227b..0d0b099627 100644
--- a/mayan/apps/ocr/models.py
+++ b/mayan/apps/ocr/models.py
@@ -14,8 +14,8 @@ class DocumentTypeSettings(models.Model):
     Define for OCR for a specific document should behave
     """
     document_type = models.OneToOneField(
-        DocumentType, on_delete=models.CASCADE, related_name='ocr_settings',
-        unique=True, verbose_name=_('Document type')
+        on_delete=models.CASCADE, related_name='ocr_settings',
+        to=DocumentType, unique=True, verbose_name=_('Document type')
     )
     auto_ocr = models.BooleanField(
         default=True,
@@ -30,8 +30,8 @@ class DocumentTypeSettings(models.Model):
 @python_2_unicode_compatible
 class DocumentPageOCRContent(models.Model):
     document_page = models.OneToOneField(
-        DocumentPage, on_delete=models.CASCADE, related_name='ocr_content',
-        verbose_name=_('Document page')
+        on_delete=models.CASCADE, related_name='ocr_content',
+        to=DocumentPage, verbose_name=_('Document page')
     )
     content = models.TextField(blank=True, verbose_name=_('Content'))
 
@@ -48,8 +48,8 @@ class DocumentPageOCRContent(models.Model):
 @python_2_unicode_compatible
 class DocumentVersionOCRError(models.Model):
     document_version = models.ForeignKey(
-        DocumentVersion, on_delete=models.CASCADE, related_name='ocr_errors',
-        verbose_name=_('Document version')
+        on_delete=models.CASCADE, related_name='ocr_errors',
+        to=DocumentVersion, verbose_name=_('Document version')
     )
     datetime_submitted = models.DateTimeField(
         auto_now_add=True, db_index=True, verbose_name=_('Date time submitted')
diff --git a/mayan/apps/permissions/models.py b/mayan/apps/permissions/models.py
index 66b58427a9..4911018b6b 100644
--- a/mayan/apps/permissions/models.py
+++ b/mayan/apps/permissions/models.py
@@ -75,10 +75,11 @@ class Role(models.Model):
         max_length=64, unique=True, verbose_name=_('Label')
     )
     permissions = models.ManyToManyField(
-        StoredPermission, related_name='roles', verbose_name=_('Permissions')
+        related_name='roles', to=StoredPermission,
+        verbose_name=_('Permissions')
     )
     groups = models.ManyToManyField(
-        Group, related_name='roles', verbose_name=_('Groups')
+        related_name='roles', to=Group, verbose_name=_('Groups')
     )
 
     objects = RoleManager()
diff --git a/mayan/apps/sources/models.py b/mayan/apps/sources/models.py
index e9bdca400b..21b6ecc710 100644
--- a/mayan/apps/sources/models.py
+++ b/mayan/apps/sources/models.py
@@ -503,18 +503,18 @@ class EmailBaseModel(IntervalBaseModel):
         ), max_length=128, verbose_name=_('Metadata attachment name')
     )
     subject_metadata_type = models.ForeignKey(
-        MetadataType, blank=True, help_text=_(
+        blank=True, help_text=_(
             'Select a metadata type valid for the document type selected in '
             'which to store the email\'s subject.'
         ), on_delete=models.CASCADE, null=True, related_name='email_subject',
-        verbose_name=_('Subject metadata type')
+        to=MetadataType, verbose_name=_('Subject metadata type')
     )
     from_metadata_type = models.ForeignKey(
-        MetadataType, blank=True, help_text=_(
+        blank=True, help_text=_(
             'Select a metadata type valid for the document type selected in '
             'which to store the email\'s "from" value.'
         ), on_delete=models.CASCADE, null=True, related_name='email_from',
-        verbose_name=_('From metadata type')
+        to=MetadataType, verbose_name=_('From metadata type')
     )
     store_body = models.BooleanField(
         default=True, help_text=_(
@@ -787,7 +787,7 @@ class WatchFolderSource(IntervalBaseModel):
 
 class SourceLog(models.Model):
     source = models.ForeignKey(
-        Source, on_delete=models.CASCADE, related_name='logs',
+        on_delete=models.CASCADE, related_name='logs', to=Source,
         verbose_name=_('Source')
     )
     datetime = models.DateTimeField(
diff --git a/mayan/apps/tags/models.py b/mayan/apps/tags/models.py
index 28528a8db3..975529454d 100644
--- a/mayan/apps/tags/models.py
+++ b/mayan/apps/tags/models.py
@@ -21,7 +21,7 @@ class Tag(models.Model):
     )
     color = RGBColorField(verbose_name=_('Color'))
     documents = models.ManyToManyField(
-        Document, related_name='tags', verbose_name=_('Documents')
+        related_name='tags', to=Document, verbose_name=_('Documents')
     )
 
     class Meta: