diff --git a/sourcing/model.py b/sourcing/model.py
index edf1aba..6d2700d 100644
--- a/sourcing/model.py
+++ b/sourcing/model.py
@@ -236,10 +236,13 @@ span: {},start=0,length={}'''.format(self.external_url, title_source_doc.externa
 
     @classmethod
     def from_external(cls, url, home=None):
+        base = current_app.config.get('BASE_URL')
         if home is None:
             home = url_for('view.home', _external=True)
         if url.startswith(home):
             username, _, hashid = url[len(home):].partition('/')
+        elif base and url.startswith(base):
+            username, _, hashid = url[len(base):].lstrip('/').partition('/')
         else:
             m = re_server_url.match(url)
             if not m: