diff --git a/sigi/apps/contatos/models.py b/sigi/apps/contatos/models.py
index 200095f..6a6f217 100644
--- a/sigi/apps/contatos/models.py
+++ b/sigi/apps/contatos/models.py
@@ -190,10 +190,13 @@ class Telefone(models.Model):
     ult_alteracao = models.DateTimeField(_(u'Última alteração'), null=True, blank=True, editable=False, auto_now=True)
 
     # guarda o tipo do objeto (classe) vinculado a esse registro
-    content_type = models.ForeignKey(ContentType)
+    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
     # identificador do registro na classe vinculado a esse registro
     object_id = models.PositiveIntegerField()
-    content_object = generic.GenericForeignKey('content_type', 'object_id')
+    content_object = generic.GenericForeignKey(
+        'content_type',
+        'object_id',
+    )
 
     class Meta:
         ordering = ('numero',)
@@ -224,10 +227,13 @@ class Contato(models.Model):
     )
 
     # guarda o tipo do objeto (classe) vinculado a esse registro
-    content_type = models.ForeignKey(ContentType)
+    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
     # identificador do registro na classe vinculado a esse registro
     object_id = models.PositiveIntegerField()
-    content_object = generic.GenericForeignKey('content_type', 'object_id')
+    content_object = generic.GenericForeignKey(
+        'content_type',
+        'object_id',
+    )
 
     class Meta:
         ordering = ('nome',)
@@ -317,10 +323,13 @@ class Endereco(models.Model):
     municipio.uf_filter = True
 
     # guarda o tipo do objeto (classe) vinculado a esse registro
-    content_type = models.ForeignKey(ContentType)
+    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
     # identificador do registro na classe vinculado a esse registro
     object_id = models.PositiveIntegerField()
-    content_object = generic.GenericForeignKey('content_type', 'object_id')
+    content_object = generic.GenericForeignKey(
+        'content_type',
+        'object_id',
+    )
 
     class Meta:
         ordering = ('logradouro', 'numero')
diff --git a/sigi/apps/inventario/models.py b/sigi/apps/inventario/models.py
index 2018769..24ecf6e 100644
--- a/sigi/apps/inventario/models.py
+++ b/sigi/apps/inventario/models.py
@@ -84,10 +84,7 @@ class Bem(models.Model):
         on_delete=models.CASCADE
     )
     equipamento = models.ForeignKey(Equipamento, on_delete=models.CASCADE)
-    fornecedor = models.ForeignKey(
-        Fornecedor,
-        on_delete=models.PROTECT
-    )
+    fornecedor = models.ForeignKey(Fornecedor, on_delete=models.PROTECT)
     num_serie = models.CharField(
         _(u'número de série'),
         max_length=64,
diff --git a/sigi/apps/servicos/models.py b/sigi/apps/servicos/models.py
index 3fe7d36..ec1733f 100644
--- a/sigi/apps/servicos/models.py
+++ b/sigi/apps/servicos/models.py
@@ -215,7 +215,7 @@ class CasaAtendida(Orgao):
 
 
 class CasaManifesta(models.Model):
-    casa_legislativa = models.OneToOneField(Orgao)
+    casa_legislativa = models.OneToOneField(Orgao, on_delete=models.CASCADE)
     data_manifestacao = models.DateTimeField(auto_now_add=True)
     data_atualizacao = models.DateTimeField(auto_now=True)
     informante = models.CharField(_(u'Nome do informante'), max_length=100, blank=True)