diff --git a/djangocms_blog/forms.py b/djangocms_blog/forms.py
index f2d4543..c1be621 100644
--- a/djangocms_blog/forms.py
+++ b/djangocms_blog/forms.py
@@ -6,7 +6,7 @@ from django.conf import settings
 from parler.forms import TranslatableModelForm
 from taggit_autosuggest.widgets import TagAutoSuggest
 
-from .models import BlogCategory, Post
+from .models import BlogCategory, BlogConfig, Post
 
 
 class LatestEntriesForm(forms.ModelForm):
@@ -35,7 +35,8 @@ class PostAdminForm(TranslatableModelForm):
         if getattr(self.instance, 'app_config_id', None):
             qs = qs.namespace(self.instance.app_config.namespace)
         elif 'initial' in kwargs and 'app_config' in kwargs['initial']:
-            qs = qs.namespace(kwargs['initial']['app_config'])
+            config = BlogConfig.objects.get(pk=kwargs['initial']['app_config'])
+            qs = qs.namespace(config.namespace)
 
         if 'categories' in self.fields:
             self.fields['categories'].queryset = qs
diff --git a/tests/test_models.py b/tests/test_models.py
index 9613bf1..5534e1a 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -128,6 +128,14 @@ class AdminTest(BaseTest):
         fsets = post_admin.get_fieldsets(request)
         self.assertTrue('author' in fsets[1][1]['fields'][0])
 
+        with self.login_user_context(self.user):
+            request = self.get_request('/', 'en', user=self.user, path=r'/en/blog/?app_config=%s' % self.app_config_1.pk)
+            msg_mid = MessageMiddleware()
+            msg_mid.process_request(request)
+            post_admin = admin.site._registry[Post]
+            response = post_admin.add_view(request)
+            self.assertContains(response, '<option value="1">category 1</option>')
+
     def test_admin_auto_author(self):
         pages = self.get_pages()
         data = deepcopy(self._post_data[0]['en'])