diff --git a/dav_events/migrations/0004_auto_20180124_1650.py b/dav_events/migrations/0004_auto_20180124_1650.py
new file mode 100644
index 0000000..be18d0b
--- /dev/null
+++ b/dav_events/migrations/0004_auto_20180124_1650.py
@@ -0,0 +1,67 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.9 on 2018-01-24 16:50
+from __future__ import unicode_literals
+
+import dav_events.models
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('dav_events', '0003_auto_20180124_1617'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='event',
+            name='accepted_at',
+            field=models.DateTimeField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='event',
+            name='accepted_by',
+            field=models.ForeignKey(blank=True, null=True, on_delete=models.SET(dav_events.models.get_ghost_user), related_name='+', to=settings.AUTH_USER_MODEL),
+        ),
+        migrations.AlterField(
+            model_name='event',
+            name='alt_first_day',
+            field=models.DateField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='event',
+            name='alt_last_day',
+            field=models.DateField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='event',
+            name='deadline',
+            field=models.DateField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='event',
+            name='last_day',
+            field=models.DateField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='event',
+            name='meeting_time',
+            field=models.TimeField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='event',
+            name='pre_meeting_1',
+            field=models.DateTimeField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='event',
+            name='pre_meeting_2',
+            field=models.DateTimeField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='event',
+            name='return_time',
+            field=models.TimeField(blank=True, null=True),
+        ),
+    ]
diff --git a/dav_events/models.py b/dav_events/models.py
index d7768e8..9973653 100644
--- a/dav_events/models.py
+++ b/dav_events/models.py
@@ -34,8 +34,10 @@ class Event(models.Model):
                               related_name='events')
     created_at = models.DateTimeField(auto_now_add=True)
     accepted = models.BooleanField(default=False)
-    accepted_at = models.DateTimeField(null=True)
+    accepted_at = models.DateTimeField(blank=True,
+                                       null=True)
     accepted_by = models.ForeignKey(settings.AUTH_USER_MODEL,
+                                    blank=True,
                                     null=True,
                                     on_delete=models.SET(get_ghost_user),
                                     related_name='+')
@@ -56,9 +58,12 @@ class Event(models.Model):
     level = models.CharField(max_length=CHOICE_FIELD_MAX_LENGTH,
                              choices=choices.LEVEL_CHOICES)
     first_day = models.DateField()
-    alt_first_day = models.DateField(null=True)
-    last_day = models.DateField(null=True)
-    alt_last_day = models.DateField(null=True)
+    alt_first_day = models.DateField(blank=True,
+                                     null=True)
+    last_day = models.DateField(blank=True,
+                                null=True)
+    alt_last_day = models.DateField(blank=True,
+                                    null=True)
 
     # TrainingForm
     course_topic_1 = models.TextField(blank=True)
@@ -89,9 +94,11 @@ class Event(models.Model):
                                      choices=choices.MEETING_POINT_CHOICES)
     meeting_point_other = models.CharField(max_length=config.MEETING_POINT_OTHER_MAX_LENGTH,
                                            blank=True)
-    meeting_time = models.TimeField(null=True)
+    meeting_time = models.TimeField(blank=True,
+                                    null=True)
     arrival_previous_day = models.BooleanField(default=False)
-    return_time = models.TimeField(null=True)
+    return_time = models.TimeField(blank=True,
+                                   null=True)
 
     basecamp = models.CharField(max_length=config.BASECAMP_MAX_LENGTH,
                                 blank=True)
@@ -108,13 +115,16 @@ class Event(models.Model):
     # RequirementsForm
     requirements = models.TextField(blank=True)
     equipment = models.TextField(blank=True)
-    pre_meeting_1 = models.DateTimeField(null=True)
-    pre_meeting_2 = models.DateTimeField(null=True)
+    pre_meeting_1 = models.DateTimeField(blank=True,
+                                         null=True)
+    pre_meeting_2 = models.DateTimeField(blank=True,
+                                         null=True)
 
     # RegistrationForm
     min_participants = models.IntegerField(default=0)
     max_participants = models.IntegerField(default=0)
-    deadline = models.DateField(null=True)
+    deadline = models.DateField(blank=True,
+                                null=True)
 
     # TrainerForm
     trainer_firstname = models.CharField(max_length=config.TRAINER_NAME_MAX_LENGTH,