diff --git a/pillar/web/nodes/finders.py b/pillar/web/nodes/finders.py
index ee413b34..c83388ff 100644
--- a/pillar/web/nodes/finders.py
+++ b/pillar/web/nodes/finders.py
@@ -66,6 +66,9 @@ def find_for_comment(project, node):
 def find_for_post(project, node):
     """Returns the URL for a blog post."""
 
+    if not node.properties:
+        raise ValueError(f'Node must have properties.url, but is {node}')
+
     project_id = project['_id']
     if str(project_id) == current_app.config['MAIN_PROJECT_ID']:
         return url_for('main.main_blog',