diff --git a/boards/forms.py b/boards/forms.py
--- a/boards/forms.py
+++ b/boards/forms.py
@@ -42,6 +42,8 @@ TAG_MAX_LENGTH = 20
 
 TEXTAREA_ROWS = 4
 
+TRIPCODE_DELIM = '#'
+
 
 def get_timezones():
     timezones = []
@@ -239,14 +241,17 @@ class PostForm(NeboardForm):
 
     def get_tripcode(self):
         title = self.cleaned_data['title']
-        if title is not None and '#' in title:
-            code = title.split('#', maxsplit=1)[1] + neboard.settings.SECRET_KEY
-            return hashlib.md5(code.encode()).hexdigest()
+        if title is not None and TRIPCODE_DELIM in title:
+            code = title.split(TRIPCODE_DELIM, maxsplit=1)[1] + neboard.settings.SECRET_KEY
+            tripcode = hashlib.md5(code.encode()).hexdigest()
+        else:
+            tripcode = ''
+        return tripcode
 
     def get_title(self):
         title = self.cleaned_data['title']
-        if title is not None and '#' in title:
-            return title.split('#', maxsplit=1)[0]
+        if title is not None and TRIPCODE_DELIM in title:
+            return title.split(TRIPCODE_DELIM, maxsplit=1)[0]
         else:
             return title
 
diff --git a/boards/migrations/0032_auto_20151014_2222.py b/boards/migrations/0032_auto_20151014_2222.py
new file mode 100644
--- /dev/null
+++ b/boards/migrations/0032_auto_20151014_2222.py
@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('boards', '0031_post_hidden'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='post',
+            name='tripcode',
+            field=models.CharField(default='', blank=True, max_length=50),
+        ),
+    ]
diff --git a/boards/migrations/0033_auto_20151014_2224.py b/boards/migrations/0033_auto_20151014_2224.py
new file mode 100644
--- /dev/null
+++ b/boards/migrations/0033_auto_20151014_2224.py
@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('boards', '0032_auto_20151014_2222'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='tag',
+            name='parent',
+            field=models.ForeignKey(blank=True, related_name='children', to='boards.Tag', null=True),
+        ),
+    ]
diff --git a/boards/models/post/__init__.py b/boards/models/post/__init__.py
--- a/boards/models/post/__init__.py
+++ b/boards/models/post/__init__.py
@@ -97,7 +97,7 @@ class Post(models.Model, Viewable):
     url = models.TextField()
     uid = models.TextField(db_index=True)
 
-    tripcode = models.CharField(max_length=50, null=True)
+    tripcode = models.CharField(max_length=50, blank=True, default='')
     opening = models.BooleanField()
     hidden = models.BooleanField(default=False)
 
diff --git a/boards/models/post/manager.py b/boards/models/post/manager.py
--- a/boards/models/post/manager.py
+++ b/boards/models/post/manager.py
@@ -30,7 +30,8 @@ NO_IP = '0.0.0.0'
 class PostManager(models.Manager):
     @transaction.atomic
     def create_post(self, title: str, text: str, file=None, thread=None,
-                    ip=NO_IP, tags: list=None, opening_posts: list=None, tripcode=None):
+                    ip=NO_IP, tags: list=None, opening_posts: list=None,
+                    tripcode=''):
         """
         Creates new post
         """
diff --git a/boards/models/tag.py b/boards/models/tag.py
--- a/boards/models/tag.py
+++ b/boards/models/tag.py
@@ -48,7 +48,8 @@ class Tag(models.Model, Viewable):
     required = models.BooleanField(default=False, db_index=True)
     description = models.TextField(blank=True)
 
-    parent = models.ForeignKey('Tag', null=True, related_name='children')
+    parent = models.ForeignKey('Tag', null=True, blank=True,
+            related_name='children')
 
     def __str__(self):
         return self.name