diff --git a/netbox/circuits/models.py b/netbox/circuits/models.py
index 6a0380dd5..5dc55d503 100644
--- a/netbox/circuits/models.py
+++ b/netbox/circuits/models.py
@@ -1,6 +1,6 @@
 from django.contrib.contenttypes.fields import GenericRelation
-from django.core.urlresolvers import reverse
 from django.db import models
+from django.urls import reverse
 from django.utils.encoding import python_2_unicode_compatible
 
 from dcim.fields import ASNField
@@ -150,7 +150,9 @@ class CircuitTermination(models.Model):
     circuit = models.ForeignKey('Circuit', related_name='terminations', on_delete=models.CASCADE)
     term_side = models.CharField(max_length=1, choices=TERM_SIDE_CHOICES, verbose_name='Termination')
     site = models.ForeignKey('dcim.Site', related_name='circuit_terminations', on_delete=models.PROTECT)
-    interface = models.OneToOneField('dcim.Interface', related_name='circuit_termination', blank=True, null=True)
+    interface = models.OneToOneField(
+        'dcim.Interface', related_name='circuit_termination', blank=True, null=True, on_delete=models.CASCADE
+    )
     port_speed = models.PositiveIntegerField(verbose_name='Port speed (Kbps)')
     upstream_speed = models.PositiveIntegerField(blank=True, null=True, verbose_name='Upstream speed (Kbps)',
                                                  help_text='Upstream speed, if different from port speed')
diff --git a/netbox/circuits/views.py b/netbox/circuits/views.py
index 1ffda899b..15903eb7e 100644
--- a/netbox/circuits/views.py
+++ b/netbox/circuits/views.py
@@ -1,10 +1,10 @@
 from django.contrib import messages
 from django.contrib.auth.decorators import permission_required
 from django.contrib.auth.mixins import PermissionRequiredMixin
-from django.core.urlresolvers import reverse
 from django.db import transaction
 from django.db.models import Count
 from django.shortcuts import get_object_or_404, redirect, render
+from django.urls import reverse
 
 from extras.models import Graph, GRAPH_TYPE_PROVIDER
 from utilities.forms import ConfirmationForm
diff --git a/netbox/dcim/models.py b/netbox/dcim/models.py
index fae85e2c1..df6f1fe57 100644
--- a/netbox/dcim/models.py
+++ b/netbox/dcim/models.py
@@ -8,10 +8,10 @@ from django.contrib.contenttypes.models import ContentType
 from django.contrib.contenttypes.fields import GenericRelation
 from django.contrib.postgres.fields import ArrayField
 from django.core.exceptions import ValidationError
-from django.core.urlresolvers import reverse
 from django.core.validators import MaxValueValidator, MinValueValidator
 from django.db import models
 from django.db.models import Count, Q, ObjectDoesNotExist
+from django.urls import reverse
 from django.utils.encoding import python_2_unicode_compatible
 
 from circuits.models import Circuit
@@ -211,7 +211,9 @@ class Region(MPTTModel):
     """
     Sites can be grouped within geographic Regions.
     """
-    parent = TreeForeignKey('self', null=True, blank=True, related_name='children', db_index=True)
+    parent = TreeForeignKey(
+        'self', null=True, blank=True, related_name='children', db_index=True, on_delete=models.CASCADE
+    )
     name = models.CharField(max_length=50, unique=True)
     slug = models.SlugField(unique=True)
 
@@ -314,7 +316,7 @@ class RackGroup(models.Model):
     """
     name = models.CharField(max_length=50)
     slug = models.SlugField()
-    site = models.ForeignKey('Site', related_name='rack_groups')
+    site = models.ForeignKey('Site', related_name='rack_groups', on_delete=models.CASCADE)
 
     class Meta:
         ordering = ['site', 'name']
diff --git a/netbox/dcim/views.py b/netbox/dcim/views.py
index e8e46d151..c356d683d 100644
--- a/netbox/dcim/views.py
+++ b/netbox/dcim/views.py
@@ -6,10 +6,10 @@ from operator import attrgetter
 from django.contrib import messages
 from django.contrib.auth.decorators import permission_required
 from django.contrib.auth.mixins import PermissionRequiredMixin
-from django.core.urlresolvers import reverse
 from django.db.models import Count
 from django.http import HttpResponseRedirect
 from django.shortcuts import get_object_or_404, redirect, render
+from django.urls import reverse
 from django.utils.http import urlencode
 from django.views.generic import View
 
diff --git a/netbox/extras/models.py b/netbox/extras/models.py
index d7889fb83..d45eac4cb 100644
--- a/netbox/extras/models.py
+++ b/netbox/extras/models.py
@@ -165,7 +165,7 @@ class CustomField(models.Model):
 
 @python_2_unicode_compatible
 class CustomFieldValue(models.Model):
-    field = models.ForeignKey('CustomField', related_name='values')
+    field = models.ForeignKey('CustomField', related_name='values', on_delete=models.CASCADE)
     obj_type = models.ForeignKey(ContentType, related_name='+', on_delete=models.PROTECT)
     obj_id = models.PositiveIntegerField()
     obj = GenericForeignKey('obj_type', 'obj_id')
@@ -254,7 +254,9 @@ class Graph(models.Model):
 
 @python_2_unicode_compatible
 class ExportTemplate(models.Model):
-    content_type = models.ForeignKey(ContentType, limit_choices_to={'model__in': EXPORTTEMPLATE_MODELS})
+    content_type = models.ForeignKey(
+        ContentType, limit_choices_to={'model__in': EXPORTTEMPLATE_MODELS}, on_delete=models.CASCADE
+    )
     name = models.CharField(max_length=100)
     description = models.CharField(max_length=200, blank=True)
     template_code = models.TextField()
@@ -294,7 +296,7 @@ class ExportTemplate(models.Model):
 class TopologyMap(models.Model):
     name = models.CharField(max_length=50, unique=True)
     slug = models.SlugField(unique=True)
-    site = models.ForeignKey('dcim.Site', related_name='topology_maps', blank=True, null=True)
+    site = models.ForeignKey('dcim.Site', related_name='topology_maps', blank=True, null=True, on_delete=models.CASCADE)
     device_patterns = models.TextField(
         help_text="Identify devices to include in the diagram using regular expressions, one per line. Each line will "
                   "result in a new tier of the drawing. Separate multiple regexes within a line using semicolons. "
@@ -384,7 +386,7 @@ class ImageAttachment(models.Model):
     """
     An uploaded image which is associated with an object.
     """
-    content_type = models.ForeignKey(ContentType)
+    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
     object_id = models.PositiveIntegerField()
     parent = GenericForeignKey('content_type', 'object_id')
     image = models.ImageField(upload_to=image_upload, height_field='image_height', width_field='image_width')
diff --git a/netbox/ipam/models.py b/netbox/ipam/models.py
index 51807d0fa..0bed7615e 100644
--- a/netbox/ipam/models.py
+++ b/netbox/ipam/models.py
@@ -3,10 +3,10 @@ from netaddr import IPNetwork, cidr_merge
 from django.conf import settings
 from django.contrib.contenttypes.fields import GenericRelation
 from django.core.exceptions import ValidationError
-from django.core.urlresolvers import reverse
 from django.core.validators import MaxValueValidator, MinValueValidator
 from django.db import models
 from django.db.models.expressions import RawSQL
+from django.urls import reverse
 from django.utils.encoding import python_2_unicode_compatible
 
 from dcim.models import Interface
diff --git a/netbox/ipam/views.py b/netbox/ipam/views.py
index 864909878..6a10859e1 100644
--- a/netbox/ipam/views.py
+++ b/netbox/ipam/views.py
@@ -5,9 +5,9 @@ from django.conf import settings
 from django.contrib.auth.decorators import permission_required
 from django.contrib.auth.mixins import PermissionRequiredMixin
 from django.contrib import messages
-from django.core.urlresolvers import reverse
 from django.db.models import Count, Q
 from django.shortcuts import get_object_or_404, redirect, render
+from django.urls import reverse
 
 from dcim.models import Device
 from utilities.forms import ConfirmationForm
diff --git a/netbox/secrets/models.py b/netbox/secrets/models.py
index 9afe2af84..2692a5113 100644
--- a/netbox/secrets/models.py
+++ b/netbox/secrets/models.py
@@ -6,8 +6,8 @@ from django.conf import settings
 from django.contrib.auth.hashers import make_password, check_password
 from django.contrib.auth.models import Group, User
 from django.core.exceptions import ValidationError
-from django.core.urlresolvers import reverse
 from django.db import models
+from django.urls import reverse
 from django.utils.encoding import force_bytes, python_2_unicode_compatible
 
 from dcim.models import Device
@@ -69,7 +69,7 @@ class UserKey(CreatedUpdatedModel):
     copy of the master encryption key. The encrypted instance of the master key can be decrypted only with the user's
     matching (private) decryption key.
     """
-    user = models.OneToOneField(User, related_name='user_key', editable=False)
+    user = models.OneToOneField(User, related_name='user_key', editable=False, on_delete=models.CASCADE)
     public_key = models.TextField(verbose_name='RSA public key')
     master_key_cipher = models.BinaryField(max_length=512, blank=True, null=True, editable=False)
 
@@ -283,7 +283,7 @@ class Secret(CreatedUpdatedModel):
     A Secret can be up to 65,536 bytes (64KB) in length. Each secret string will be padded with random data to a minimum
     of 64 bytes during encryption in order to protect short strings from ciphertext analysis.
     """
-    device = models.ForeignKey(Device, related_name='secrets')
+    device = models.ForeignKey(Device, related_name='secrets', on_delete=models.CASCADE)
     role = models.ForeignKey('SecretRole', related_name='secrets', on_delete=models.PROTECT)
     name = models.CharField(max_length=100, blank=True)
     ciphertext = models.BinaryField(editable=False, max_length=65568)  # 16B IV + 2B pad length + {62-65550}B padded
diff --git a/netbox/secrets/views.py b/netbox/secrets/views.py
index 308e9de3d..653fd06fe 100644
--- a/netbox/secrets/views.py
+++ b/netbox/secrets/views.py
@@ -3,10 +3,10 @@ import base64
 from django.contrib import messages
 from django.contrib.auth.decorators import permission_required, login_required
 from django.contrib.auth.mixins import PermissionRequiredMixin
-from django.core.urlresolvers import reverse
 from django.db import transaction, IntegrityError
 from django.db.models import Count
 from django.shortcuts import get_object_or_404, redirect, render
+from django.urls import reverse
 from django.utils.decorators import method_decorator
 
 from dcim.models import Device
diff --git a/netbox/tenancy/models.py b/netbox/tenancy/models.py
index df871fc31..203dc7e41 100644
--- a/netbox/tenancy/models.py
+++ b/netbox/tenancy/models.py
@@ -1,6 +1,6 @@
 from django.contrib.contenttypes.fields import GenericRelation
-from django.core.urlresolvers import reverse
 from django.db import models
+from django.urls import reverse
 from django.utils.encoding import python_2_unicode_compatible
 
 from extras.models import CustomFieldModel, CustomFieldValue
diff --git a/netbox/tenancy/views.py b/netbox/tenancy/views.py
index f4bb05b69..0f70fa6d0 100644
--- a/netbox/tenancy/views.py
+++ b/netbox/tenancy/views.py
@@ -1,7 +1,7 @@
 from django.contrib.auth.mixins import PermissionRequiredMixin
-from django.core.urlresolvers import reverse
 from django.db.models import Count, Q
 from django.shortcuts import get_object_or_404, render
+from django.urls import reverse
 
 from circuits.models import Circuit
 from dcim.models import Site, Rack, Device
diff --git a/netbox/users/views.py b/netbox/users/views.py
index 711c5a9c0..03e913742 100644
--- a/netbox/users/views.py
+++ b/netbox/users/views.py
@@ -2,9 +2,9 @@ from django.contrib import messages
 from django.contrib.auth import login as auth_login, logout as auth_logout, update_session_auth_hash
 from django.contrib.auth.decorators import login_required
 from django.contrib.auth.mixins import LoginRequiredMixin
-from django.core.urlresolvers import reverse
 from django.http import HttpResponseRedirect
 from django.shortcuts import get_object_or_404, redirect, render
+from django.urls import reverse
 from django.utils.http import is_safe_url
 from django.views.generic import View
 
diff --git a/netbox/utilities/forms.py b/netbox/utilities/forms.py
index 6813c0553..05e7a528e 100644
--- a/netbox/utilities/forms.py
+++ b/netbox/utilities/forms.py
@@ -6,8 +6,8 @@ from mptt.forms import TreeNodeMultipleChoiceField
 
 from django import forms
 from django.conf import settings
-from django.core.urlresolvers import reverse_lazy
 from django.core.validators import URLValidator
+from django.urls import reverse_lazy
 
 
 COLOR_CHOICES = (
diff --git a/netbox/utilities/middleware.py b/netbox/utilities/middleware.py
index 4ebfee3ed..22697d179 100644
--- a/netbox/utilities/middleware.py
+++ b/netbox/utilities/middleware.py
@@ -1,6 +1,6 @@
 from django.http import HttpResponseRedirect
 from django.conf import settings
-from django.core.urlresolvers import reverse
+from django.urls import reverse
 
 
 BASE_PATH = getattr(settings, 'BASE_PATH', False)
diff --git a/netbox/utilities/views.py b/netbox/utilities/views.py
index 1c3e74b30..0bf56f0fe 100644
--- a/netbox/utilities/views.py
+++ b/netbox/utilities/views.py
@@ -5,13 +5,13 @@ from django.conf import settings
 from django.contrib import messages
 from django.contrib.contenttypes.models import ContentType
 from django.core.exceptions import ValidationError
-from django.core.urlresolvers import reverse
 from django.db import transaction, IntegrityError
 from django.db.models import ProtectedError
 from django.forms import CharField, ModelMultipleChoiceField, MultipleHiddenInput, TypedChoiceField
 from django.http import HttpResponse
 from django.shortcuts import get_object_or_404, redirect, render
 from django.template import TemplateSyntaxError
+from django.urls import reverse
 from django.utils.http import is_safe_url
 from django.views.generic import View