diff --git a/caldav_sync/__manifest__.py b/caldav_sync/__manifest__.py
index 6a75a66..c3bb355 100644
--- a/caldav_sync/__manifest__.py
+++ b/caldav_sync/__manifest__.py
@@ -17,6 +17,9 @@
     """,
     'author': 'Your Name',
     'depends': ['base', 'calendar'],
+    'external_dependencies': {
+        'python': ['caldav'],
+    },
     'data': [
         'data/caldav_sync_data.xml',
     ],
diff --git a/caldav_sync/controllers/main.py b/caldav_sync/controllers/main.py
index bf16280..97ca3c1 100644
--- a/caldav_sync/controllers/main.py
+++ b/caldav_sync/controllers/main.py
@@ -7,8 +7,8 @@ from datetime import datetime
 
 _logger = logging.getLogger(__name__)
 
-class CaldavController(http.Controller):
 
+class CaldavController(http.Controller):
     @http.route('/caldav_sync/sync', type='json', auth='user')
     def sync(self, **kwargs):
         # Fetch user credentials and server settings from Odoo
@@ -30,7 +30,8 @@ class CaldavController(http.Controller):
 
         return {'status': 'success', 'message': 'Synchronization completed'}
 
-    def sync_event(self, ical):
+    @staticmethod
+    def sync_event(ical):
         event = ical.subcomponents[0]
         uid = event['UID']
         start = event['DTSTART'].dt