diff --git a/sapl/materia/forms.py b/sapl/materia/forms.py
index 5dc0d0920..468426a13 100644
--- a/sapl/materia/forms.py
+++ b/sapl/materia/forms.py
@@ -8,8 +8,7 @@ from crispy_forms.layout import (HTML, Button, Column, Div, Field, Fieldset,
                                  Layout, Submit)
 from django import forms
 from django.contrib.contenttypes.models import ContentType
-from django.core.exceptions import ObjectDoesNotExist, ValidationError,\
-    NON_FIELD_ERRORS
+from django.core.exceptions import ObjectDoesNotExist, ValidationError
 from django.core.files.base import File
 from django.core.urlresolvers import reverse
 from django.db import models, transaction
@@ -820,8 +819,12 @@ class TipoProposicaoForm(ModelForm):
                   ) % (cd['tipo_conteudo_related'], content_type))
 
         unique_value = self._meta.model.objects.filter(
-            content_type=content_type, object_id=cd['tipo_conteudo_related']
-        ).first()
+            content_type=content_type, object_id=cd['tipo_conteudo_related'])
+
+        if self.instance.pk:
+            unique_value = unique_value.exclude(pk=self.instance.pk)
+
+        unique_value = unique_value.first()
 
         if unique_value:
             raise ValidationError(
@@ -831,7 +834,7 @@ class TipoProposicaoForm(ModelForm):
                        content_type,
                        unique_value.tipo_conteudo_related))
 
-        return self.cleaned_data
+        return super().clean()
 
     @transaction.atomic
     def save(self, commit=False):
diff --git a/sapl/materia/migrations/0007_auto_20170620_1252.py b/sapl/materia/migrations/0007_auto_20170620_1252.py
new file mode 100644
index 000000000..6d19ee4da
--- /dev/null
+++ b/sapl/materia/migrations/0007_auto_20170620_1252.py
@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.13 on 2017-06-20 12:52
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('materia', '0006_merge'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='tipoproposicao',
+            name='descricao',
+            field=models.CharField(error_messages={'unique': 'Já existe um Tipo de Proposição com esta descrição.'}, max_length=50, unique=True, verbose_name='Descrição'),
+        ),
+    ]
diff --git a/sapl/materia/models.py b/sapl/materia/models.py
index 6b02f2f14..f6d9ab619 100644
--- a/sapl/materia/models.py
+++ b/sapl/materia/models.py
@@ -34,7 +34,13 @@ def grupo_autor():
 
 @reversion.register()
 class TipoProposicao(models.Model):
-    descricao = models.CharField(max_length=50, verbose_name=_('Descrição'))
+    descricao = models.CharField(
+        max_length=50,
+        verbose_name=_('Descrição'),
+        unique=True,
+        error_messages={
+            'unique': _('Já existe um Tipo de Proposição com esta descrição.')
+        })
 
     # FIXME - para a rotina de migração - estes campos mudaram
     # retire o comentário quando resolver