diff --git a/cfp/migrations/0006_auto_20170811_1457.py b/cfp/migrations/0006_auto_20170811_1457.py
new file mode 100644
index 0000000..f084e8c
--- /dev/null
+++ b/cfp/migrations/0006_auto_20170811_1457.py
@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.3 on 2017-08-11 14:57
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import uuid
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('cfp', '0005_conference_reply_email'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='participant',
+            name='token',
+            field=models.UUIDField(default=uuid.uuid4, editable=False, unique=True),
+        ),
+        migrations.AlterField(
+            model_name='talk',
+            name='token',
+            field=models.UUIDField(default=uuid.uuid4, editable=False, unique=True),
+        ),
+    ]
diff --git a/cfp/models.py b/cfp/models.py
index 38c992a..0ba42b5 100644
--- a/cfp/models.py
+++ b/cfp/models.py
@@ -82,7 +82,7 @@ class Participant(PonyConfModel):
     email = models.EmailField()
 
     biography = models.TextField(verbose_name=_('Biography'))
-    token = models.UUIDField(default=uuid.uuid4, editable=False)
+    token = models.UUIDField(default=uuid.uuid4, editable=False, unique=True)
 
     twitter = models.CharField(max_length=100, blank=True, default='', verbose_name=_('Twitter'))
     linkedin = models.CharField(max_length=100, blank=True, default='', verbose_name=_('LinkedIn'))
@@ -267,7 +267,7 @@ class Talk(PonyConfModel):
     #materials = models.FileField(null=True, upload_to=talk_materials_destination, verbose_name=_('Materials'),
     #                             help_text=_('You can use this field to share some materials related to your intervention.'))
 
-    token = models.UUIDField(default=uuid.uuid4, editable=False)
+    token = models.UUIDField(default=uuid.uuid4, editable=False, unique=True)
 
     conversation = models.OneToOneField(MessageThread)