diff --git a/website/web/__init__.py b/website/web/__init__.py
index aa38e3e0..5be94e54 100644
--- a/website/web/__init__.py
+++ b/website/web/__init__.py
@@ -771,7 +771,7 @@ def _prepare_capture_template(user_ua: Optional[str], predefined_url: Optional[s
         flash('The request will be enqueued, but capturing may take a while and require the administrator to wake up.', 'error')
     return render_template('capture.html', user_agents=user_agents, default=default_ua,
                            max_depth=max_depth, personal_ua=user_ua,
-                           predefined_url_to_capture=predefined_url)
+                           predefined_url_to_capture=predefined_url if predefined_url else '')
 
 
 @app.route('/recapture/<string:tree_uuid>', methods=['GET'])