diff --git a/backend/__init__.py b/backend/__init__.py
index ce2c20eb..602c446d 100644
--- a/backend/__init__.py
+++ b/backend/__init__.py
@@ -483,8 +483,13 @@ def changedetection_app(config=None, datastore_o=None):
     def api_watch_add():
         global messages
 
+        url = request.form.get('url').strip()
+        if datastore.url_exists(url):
+            messages.append({'class': 'error', 'message': 'The URL {} already exists'.format(url)})
+            return redirect(url_for('index'))
+
         # @todo add_watch should throw a custom Exception for validation etc
-        new_uuid = datastore.add_watch(url=request.form.get('url').strip(), tag=request.form.get('tag').strip())
+        new_uuid = datastore.add_watch(url=url, tag=request.form.get('tag').strip())
         # Straight into the queue.
         update_q.put(new_uuid)
 
diff --git a/backend/store.py b/backend/store.py
index be5875fc..e51a0f61 100644
--- a/backend/store.py
+++ b/backend/store.py
@@ -211,7 +211,7 @@ class ChangeDetectionStore:
     def url_exists(self, url):
 
         # Probably their should be dict...
-        for watch in self.data['watching']:
+        for watch in self.data['watching'].values():
             if watch['url'] == url:
                 return True