diff --git a/vendor/symposion/sponsorship/models.py b/vendor/symposion/sponsorship/models.py
index cd256d11b7a1ca58a52dbd7957e1a20236c61062..4cc8efe81e44015da1669008961ca757e5e97922 100644
--- a/vendor/symposion/sponsorship/models.py
+++ b/vendor/symposion/sponsorship/models.py
@@ -2,16 +2,18 @@ import datetime
 
 from django.conf import settings
 from django.core.exceptions import ValidationError
-from django.core.urlresolvers import reverse
 from django.db import models
 from django.db.models.signals import post_init, post_save
+from django.urls import reverse
 from django.utils.translation import ugettext_lazy as _
 
-from django.contrib.auth.models import User
+from django.contrib.auth import get_user_model
 
 from symposion.conference.models import Conference
 from symposion.sponsorship.managers import SponsorManager
 
+User = get_user_model()
+
 
 # The benefits we track as individual fields on sponsors
 # Names are the names in the database as defined by organizers.
@@ -44,7 +46,11 @@ BENEFITS = [
 
 class SponsorLevel(models.Model):
 
-    conference = models.ForeignKey(Conference, verbose_name=_("Conference"))
+    conference = models.ForeignKey(
+        Conference,
+        verbose_name=_("Conference"),
+        on_delete=models.CASCADE,
+    )
     name = models.CharField(_("Name"), max_length=100)
     order = models.IntegerField(_("Order"), default=0)
     cost = models.PositiveIntegerField(_("Cost"))
@@ -64,8 +70,13 @@ class SponsorLevel(models.Model):
 
 class Sponsor(models.Model):
 
-    applicant = models.ForeignKey(User, related_name="sponsorships", verbose_name=_("Applicant"),
-                                  null=True)
+    applicant = models.ForeignKey(
+        User,
+        related_name="sponsorships",
+        verbose_name=_("Applicant"),
+        null=True,
+        on_delete=models.CASCADE,
+    )
 
     name = models.CharField(_("Sponsor Name"), max_length=100)
     display_url = models.URLField(_("display URL"), blank=True)
@@ -73,13 +84,24 @@ class Sponsor(models.Model):
     annotation = models.TextField(_("Annotation"), blank=True)
     contact_name = models.CharField(_("Contact Name"), max_length=100)
     contact_email = models.EmailField(_("Contact Email"))
-    level = models.ForeignKey(SponsorLevel, verbose_name=_("level"))
+    level = models.ForeignKey(
+        SponsorLevel,
+        verbose_name=_("level"),
+        on_delete=models.CASCADE,
+    )
     added = models.DateTimeField(_("added"), default=datetime.datetime.now)
     active = models.BooleanField(_("active"), default=False)
 
     # Denormalization (this assumes only one logo)
-    sponsor_logo = models.ForeignKey("SponsorBenefit", related_name="+", null=True, blank=True,
-                                     editable=False, verbose_name=_("Sponsor logo"))
+    sponsor_logo = models.ForeignKey(
+        "SponsorBenefit",
+        related_name="+",
+        null=True,
+        blank=True,
+        editable=False,
+        verbose_name=_("Sponsor logo"),
+        on_delete=models.CASCADE,
+    )
 
     # Whether things are complete
     # True = complete, False = incomplate, Null = n/a for this sponsor level
@@ -242,8 +264,18 @@ class Benefit(models.Model):
 
 class BenefitLevel(models.Model):
 
-    benefit = models.ForeignKey(Benefit, related_name="benefit_levels", verbose_name=_("Benefit"))
-    level = models.ForeignKey(SponsorLevel, related_name="benefit_levels", verbose_name=_("Level"))
+    benefit = models.ForeignKey(
+        Benefit,
+        related_name="benefit_levels",
+        verbose_name=_("Benefit"),
+        on_delete=models.CASCADE,
+    )
+    level = models.ForeignKey(
+        SponsorLevel,
+        related_name="benefit_levels",
+        verbose_name=_("Level"),
+        on_delete=models.CASCADE,
+    )
 
     # default limits for this benefit at given level
     max_words = models.PositiveIntegerField(_("Max words"), blank=True, null=True)
@@ -260,8 +292,18 @@ class BenefitLevel(models.Model):
 
 class SponsorBenefit(models.Model):
 
-    sponsor = models.ForeignKey(Sponsor, related_name="sponsor_benefits", verbose_name=_("Sponsor"))
-    benefit = models.ForeignKey(Benefit, related_name="sponsor_benefits", verbose_name=_("Benefit"))
+    sponsor = models.ForeignKey(
+        Sponsor,
+        related_name="sponsor_benefits",
+        verbose_name=_("Sponsor"),
+        on_delete=models.CASCADE,
+    )
+    benefit = models.ForeignKey(
+        Benefit,
+        related_name="sponsor_benefits",
+        verbose_name=_("Benefit"),
+        on_delete=models.CASCADE,
+    )
     active = models.BooleanField(default=True, verbose_name=_("Active"))
 
     # Limits: will initially be set to defaults from corresponding BenefitLevel