diff --git a/integrations/mongodb_atlas/src/haystack_integrations/document_stores/mongodb_atlas/document_store.py b/integrations/mongodb_atlas/src/haystack_integrations/document_stores/mongodb_atlas/document_store.py
index 88eec4aed..93eb87005 100644
--- a/integrations/mongodb_atlas/src/haystack_integrations/document_stores/mongodb_atlas/document_store.py
+++ b/integrations/mongodb_atlas/src/haystack_integrations/document_stores/mongodb_atlas/document_store.py
@@ -82,7 +82,6 @@ def __init__(
             msg = f'Invalid collection name: "{collection_name}". It can only contain letters, numbers, -, or _.'
             raise ValueError(msg)
 
-        self.resolved_connection_string = mongo_connection_string.resolve_value()
         self.mongo_connection_string = mongo_connection_string
 
         self.database_name = database_name
@@ -95,7 +94,7 @@ def __init__(
     def connection(self) -> MongoClient:
         if self._connection is None:
             self._connection = MongoClient(
-                self.resolved_connection_string, driver=DriverInfo(name="MongoDBAtlasHaystackIntegration")
+                self.mongo_connection_string.resolve_value(), driver=DriverInfo(name="MongoDBAtlasHaystackIntegration")
             )
 
         return self._connection