diff --git a/src/aki_prj23_transparenzregister/utils/mongo.py b/src/aki_prj23_transparenzregister/utils/mongo.py
index cac9e26..ab5e1e8 100644
--- a/src/aki_prj23_transparenzregister/utils/mongo.py
+++ b/src/aki_prj23_transparenzregister/utils/mongo.py
@@ -41,5 +41,7 @@ class MongoConnector:
         Args:
             connection (MongoConnection): Wrapper for connection string
         """
-        self.client = pymongo.MongoClient(connection.get_conn_string())
+        self.client: pymongo.MongoClient = pymongo.MongoClient(
+            connection.get_conn_string()
+        )
         self.database = self.client[connection.database]