diff --git a/mellon/migrations/0001_initial.py b/mellon/migrations/0001_initial.py
index eca7a91..73a2a7f 100644
--- a/mellon/migrations/0001_initial.py
+++ b/mellon/migrations/0001_initial.py
@@ -19,7 +19,7 @@ class Migration(migrations.Migration):
                 ('issuer', models.TextField(verbose_name='Issuer')),
                 ('name_id', models.TextField(verbose_name='SAML identifier')),
                 ('created', models.DateTimeField(auto_now_add=True, verbose_name='created')),
-                ('user', models.ForeignKey(related_name='saml_identifiers', verbose_name='user', to=settings.AUTH_USER_MODEL)),
+                ('user', models.ForeignKey(related_name='saml_identifiers', verbose_name='user', to=settings.AUTH_USER_MODEL, on_delete=models.CASCADE)),
             ],
             options={
                 'verbose_name': 'user SAML identifier',
diff --git a/mellon/models.py b/mellon/models.py
index 02315ca..8e52c13 100644
--- a/mellon/models.py
+++ b/mellon/models.py
@@ -24,7 +24,8 @@ class UserSAMLIdentifier(models.Model):
     user = models.ForeignKey(
         verbose_name=_('user'),
         to=settings.AUTH_USER_MODEL,
-        related_name='saml_identifiers')
+        related_name='saml_identifiers',
+        on_delete=models.CASCADE)
     issuer = models.TextField(
         verbose_name=_('Issuer'))
     name_id = models.TextField(