diff --git a/core/fixtures/groups.json b/core/fixtures/groups.json
new file mode 100644
index 00000000..8ac77e46
--- /dev/null
+++ b/core/fixtures/groups.json
@@ -0,0 +1 @@
+[{"pk": 1, "model": "auth.group", "fields": {"name": "root", "permissions": [1, 2, 3, 7, 8, 9, 4, 5, 6, 10, 11, 12, 19, 20, 21, 16, 17, 18, 13, 14, 15]}}]
\ No newline at end of file
diff --git a/core/models.py b/core/models.py
index 49a19960..d095123b 100644
--- a/core/models.py
+++ b/core/models.py
@@ -174,6 +174,21 @@ class Page(models.Model):
                 code='duplicate',
             )
         super(Page, self).clean()
+        if self.parent is not None and self in self.get_parent_list():
+            raise ValidationError(
+                _('Loop in page tree'),
+                code='loop',
+            )
+
+    def get_parent_list(self):
+        l = []
+        p = self.parent
+        while p is not None:
+            l.append(p)
+            p = p.parent
+        return l
+
+
 
     def save(self, *args, **kwargs):
         self.full_clean()
diff --git a/core/views/site.py b/core/views/site.py
index d0c94464..7f237928 100644
--- a/core/views/site.py
+++ b/core/views/site.py
@@ -1,11 +1,6 @@
 from django.shortcuts import render, redirect, get_object_or_404
 from django.http import HttpResponse
-from django.contrib.auth import logout as auth_logout
 from django.db import models
-from django.contrib.auth.forms import PasswordChangeForm
-
-from core.models import User, Page
-from core.views.forms import RegisteringForm, LoginForm, UserEditForm, PageEditForm, PagePropForm
 
 import logging
 
diff --git a/core/views/user.py b/core/views/user.py
index a915759d..007eb844 100644
--- a/core/views/user.py
+++ b/core/views/user.py
@@ -1,8 +1,11 @@
 # This file contains all the views that concern the user model
 from django.shortcuts import render, redirect, get_object_or_404
+from django.contrib.auth import logout as auth_logout
+from django.contrib.auth.forms import PasswordChangeForm
 import logging
 
-from core.views.forms import RegisteringForm, LoginForm
+from core.views.forms import RegisteringForm, LoginForm, UserEditForm
+from core.models import User
 
 def register(request):
     context = {'title': 'Register a user'}